WO2022220932A2

WO2022220932A2 - Plasma generation systems and methods with enhanced electrode configurations

Info

Publication number: WO2022220932A2
Application number: PCT/US2022/017858
Authority: WO
Inventors: Raymond Golingo; Zahra SEIFOLLAHI MOGHADAM; Ayan CHOUDHURY
Original assignee: Fuse Energy Technologies Corp.
Priority date: 2021-02-26
Filing date: 2022-02-25
Publication date: 2022-10-20
Also published as: WO2022220932A3

Abstract

Plasma generation systems and methods with enhanced electrode configurations are disclosed. The system can include a plasma confinement device extending along a Z-pinch axis and including an inner electrode having at least two inner electrode segments disposed successively axially, and an outer electrode including at least two outer electrode segments disposed successively axially. The outer electrode surrounds the inner electrode to define therebetween an acceleration region configured to contain a source plasma and extends forwardly beyond the inner electrode to define an assembly region adjacent the acceleration region. The system can also include a power supply unit including at least two power supplies, each of which configured to apply a voltage between a respective inner electrode segment and a respective outer electrode segment. The application of the voltages causes the source plasma to flow along the acceleration region and into the assembly region to be compressed into a Z-pinch plasma.

Description

PLASMA GENERATION SYSTEMS AND METHODS WITH ENHANCED ELECTRODE

CONFIGURATIONS

CROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] The present application claims priority to U.S. Provisional Patent Application No. 63/154,261 filed on February 26, 2021, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] The technical field generally relates to plasma technology and, more particularly, to plasma generation systems and methods with enhanced electrode configurations for use, for example, in fusion power applications.

BACKGROUND

[0003] Nuclear fusion energy is energy produced by a nuclear fusion process in which tw o or more lighter atomic nuclei are joined to form a heavier nucleus whose mass is less than the sum of the masses of the lighter nuclei. The difference in mass is released as energy, which can be harnessed to produce electricity. Fusion reactors are devices whose function is to harness fusion energy. One type of fusion reactors relies on magnetic plasma confinement. Such fusion reactors aim to confine high-temperature plasmas to sufficiently high-density with prolonged stability. Non-limiting examples of magnetic plasma confinement approaches include Z-pinch-configurations, magnetic mirror configurations, and toroidal configurations, for example, the tokamak and the stellarator. In Z-pinch configurations, a plasma column with an axial current flowing through it generates an azimuthal magnetic field that radially compresses the plasma, resulting in an increase of the fusion reaction rate. Z-pinch reactors are attractive due to their simple geometry, absence of magnetic field coils for plasma confinement and stabilization, inherent compactness, and relatively low cost. Conventional Z-pinch reactors suffer from instabilities that limit plasma lifetimes. Recent research has found that stabilization of the plasma with a sheared flow can help reduce these instabilities, opening up the possibility of producing and sustaining stable Z-pinches over longer timescales. However, despite these advances, challenges remain in the field of Z-pinch-based fusion devices.

SUMMARY

[0004] The present description generally relates to plasma generation systems and methods using segmented electrodes.

[0005] In accordance with an aspect, there is provided a plasma generation system including: a plasma confinement device extending along a longitudinal Z-pinch axis and including: an inner electrode extending longitudinally between a front end and a rear end, the inner electrode including at least two inner electrode segments disposed successively along the Z-pinch axis; and an outer electrode extending longitudinally between a front end and a rear end, the outer electrode including at least two outer electrode segments disposed successively along the Z-pinch axis, the outer electrode surrounding the inner electrode to define therebetween an acceleration region configured to contain a source plasma, the outer electrode extending forwardly beyond the inner electrode along the Z-pinch axis to define an assembly region adjacent the acceleration region and extending between the front end of the inner electrode and the front end of the outer electrode; and a power supply unit including at least two power supplies, each power supply being configured to apply a respective one of at least two voltages between one of the at least two inner electrode segments and one of the at least two outer electrode segments, wherein the application of the at least two voltages causes the source plasma to flow' along the acceleration region and into the assembly region and to be compressed into a Z-pinch plasma along the Z-pinch axis in the assembly region.

[0006] In some embodiments, the at least tw o inner electrode segments include between two and four inner electrode segments, the at least two outer electrode segments include between two and four outer electrode segments, and the at least two power supplies include between two and four power supplies. In some embodiments, the plasma generation system further includes at least one inner segment insulator longitudinally interleaved with the at least two inner electrode segments, and at least one outer segment insulator longitudinally interleaved with the at least two outer electrode segments.

[0007] In some embodiments, the plasma generation system further includes a process gas supply unit configured to supply a process gas inside the acceleration region via a process gas injection port formed in the plasma confinement device, the at least two inner electrode segments include a first inner electrode segment; the at least two outer electrode segments include a first outer electrode segment; and the at least two pow er supplies include a first power supply configured to apply a first voltage of the at least two voltages between the first inner electrode segment and the first outer electrode segment to generate an ionization current configured to ionize the process gas injected inside the acceleration region into the source plasma. In some embodiments, the gas injection port is formed through the inner electrode or through the outer electrode. In some embodiments, the plasma injection port is formed through the rearmost one of the at least two inner electrode segments or through rearmost one of the at least two outer electrode segments. In some embodiments, the process gas includes deuterium, tritium, hydrogen, or helium, or any combination thereof

[0008] In some embodiments, the at least tw o inner electrode segments further include a second inner electrode segment disposed forwardly of the first inner electrode segment; the at least two outer electrode segments further include a second outer electrode segment disposed forwardly of the first outer electrode segment; the first power supply is further configured to apply the first voltage between the first inner electrode segment and the first outer electrode segment to generate an acceleration current configured to accelerate the source plasma along the acceleration region; and the at least two power supplies further include a second power supply configured to apply a second voltage of the at least two voltages between the second inner electrode segment and the second outer electrode segment to generate a turning current configured to turn the source plasma inwardly toward the Z-pinch axis in the assembly region and a Z-pinch current configured to flow along the Z-pinch plasma. In some embodiments, the second outer electrode segment extends partly forwardly of the front end of the inner electrode. In some embodiments, the first power supply is configured to start applying the first voltage before the second power supply is configured to start applying the second voltage. In some embodiments, an inner segment insulator interposed between the first and second inner electrode segments is longitudinally aligned with an outer segment insulator interposed between the first and second outer electrode segments.

[0009] In some embodiments, the at least two inner electrode segments further include a second inner electrode segment disposed forwardly of the first inner electrode segment, and a third inner electrode segment disposed forwardly of the second inner electrode segment; the at least two outer electrode segments further include a second outer electrode segment disposed forwardly of the first outer electrode segment, and a third outer electrode segment disposed forwardly of the second outer electrode segment; and the at least two power supplies further include: a second power supply configured to apply a second voltage of the at least two voltages between the second inner electrode segment and the second outer electrode segment to generate an acceleration current configured to accelerate the source plasma along the acceleration region; and a third power supply configured to apply a third voltage of the at least two voltages between the third inner electrode segment and the third outer electrode segment to generate a turning current configured to turn the source plasma inwardly toward the Z-pinch axis in the assembly region and a Z-pinch current configured to flow along the Z-pinch plasma. In some embodiments, the second outer electrode segment extends entirely rearwardly of the front end of the inner electrode, and the third outer electrode segment extends partly forwardly of the front end of the inner electrode. In some embodiments, the first power supply is configured to start applying the first voltage before the second power supply is configured to start applying the second voltage, and the second power supply is configured to start applying the second voltage before the third power supply is configured to start applying the third voltage. In some embodiments, a first inner segment insulator interposed between the first and second inner electrode segments is longitudinally aligned with a first outer segment insulator interposed between the first and second outer electrode segments, and a second inner segment insulator interposed between the second and third inner electrode segments is longitudinally aligned with a second outer segment insulator interposed between the second and third outer electrode segments. [0010] In some embodiments, the at least tw o inner electrode segments further include a second inner electrode segment disposed forwardly of the first inner electrode segment, a third inner electrode segment disposed forwardly of the second inner electrode segment, and a fourth inner electrode segment disposed forwardly of the third inner electrode segment; the at least two outer electrode segments further include a second outer electrode segment disposed forwardly of the first outer electrode segment, a third outer electrode segment disposed forw ardly of the second outer electrode segment, and a fourth outer electrode segment disposed forwardly of the fourth outer electrode segment; and the at least two power supplies further include: a second power supply configured to apply a second voltage of the at least two voltages between the second inner electrode segment and the second outer electrode segment to generate an acceleration current configured to accelerate the source plasma along the acceleration region; a third power supply configured to apply a third voltage of the at least two voltages between the third inner electrode segment and the third outer electrode segment to generate a turning current configured to turn the source plasma inwardly toward the Z-pinch axis in the assembly region; and a fourth power supply configured to apply a fourth voltage of the at least two voltages between the fourth inner electrode segment and the fourth outer electrode segment to generate a Z-pinch current configured to flow along the Z-pinch plasma. In some embodiments, the second outer electrode segment extends entirely rearwardly of the front end of the inner electrode, the third outer electrode segment extends partly forwardly of the front end of the inner electrode, and the fourth outer electrode segment extends entirely forwardly of the front end of the inner electrode. In some embodiments, the first power supply is configured to start applying the first voltage before the second power supply is configured to start applying the second voltage, the second power supply is configured to start applying the second voltage before the third power supply is configured to start applying the third voltage, and the third power supply is configured to start applying the third voltage before the fourth power supply is configured to start applying the fourth voltage. In some embodiments, a first inner segment insulator interposed between the first and second inner electrode segments is longitudinally aligned with a first outer segment insulator interposed between the first and second outer electrode segments, a second inner segment insulator interposed between the second and third inner electrode segments is longitudinally aligned with a second outer segment insulator interposed between the second and third outer electrode segments, and a third inner segment insulator interposed between the third and fourth inner electrode segments is rearwardly disposed with respect to a third outer segment insulator interposed between the third and fourth outer electrode segments.

[0011] In some embodiments, the plasma generation system further includes a plasma formation and injection device including a plasma generator configured to generate the source plasma and inject the source plasma inside the acceleration region via a plasma injection port formed through the plasma confinement device. In some embodiments, the plasma injection port is formed through the rearmost one of the at least two inner electrode segments or through the rearmost one of the at least two outer electrode segments. In some embodiments, the plasma generator includes a plurality of plasma generators and the plasma injection port includes a plurality of plasma injection ports, each plasma generator being configured to generate a respective portion of the source plasma and inject the respective portion of the source inside the acceleration region via a respective one a plurality of plasma injection ports. In some embodiments, the plasma generator includes an inner electrode, and an outer electrode surrounding the inner electrode to define a plasma formation region therebetween, the outer electrode extending beyond the inner electrode along a plasma formation axis to enclose a plasma transport channel extending from the plasma formation region to the plasma injection port along the plasma formation axis. In some embodiments, the plasma formation and injection device includes a process gas supply unit configured to supply a process gas into the plasma formation region, and a plasma formation power supply configured to apply a voltage between the inner electrode and the outer electrode of the plasma generator to energize the process gas into the source plasma and cause the source plasma to flow along the plasma formation region and through the plasma transport channel to reach the plasma injection port for injection of the source plasma inside the acceleration region. In some embodiments, the process gas includes deuterium, tritium, hydrogen, or helium, or any combination thereof.

[0012] In some embodiments, the at least two inner electrode segments include a first inner electrode segment and a second inner electrode segment disposed forwardly of the first inner electrode segment; the at least two outer electrode segments include a first outer electrode segment and a second outer electrode segment disposed forwardly of the first outer electrode segment; and the at least two power supplies further include: a first power supply configured to apply a first voltage of the at least two voltages between the first inner electrode segment and the first outer electrode segment to generate an acceleration current configured to accelerate the source plasma along the acceleration region; and a second power supply configured to apply a second voltage of the at least two voltages between the second inner electrode segment and the second outer electrode segment to generate a turning current configured to turn the source plasma inwardly toward the Z-pinch axis in the assembly region and a Z- pinch current configured to flow along the Z-pinch plasma. In some embodiments, the second outer electrode segment extends partly forwardly of the front end of the inner electrode. In some embodiments, the first power supply is configured to start applying the first voltage before the second power supply is configured to start applying the second voltage. In some embodiments, an inner segment insulator interposed between the first and second inner electrode segments is longitudinally aligned with an outer segment insulator interposed between the first and second outer electrode segments.

[0013] In some embodiments, the at least two inner electrode segments include a first inner electrode segment, a second inner electrode segment disposed forwardly of the first inner electrode segment, and a third inner electrode segment disposed forwardly of the second inner electrode segment; the at least two outer electrode segments include a first outer electrode segment, a second outer electrode segment disposed forwardly of the first outer electrode segment, and a third outer electrode segment disposed forwardly of the second outer electrode segment; and the at least two power supplies further include: a first power supply configured to apply a first voltage of the at least two voltages between the first inner electrode segment and the first outer electrode segment to generate an acceleration current configured to accelerate the source plasma along the acceleration region; a second power supply configured to apply a second voltage of the at least two voltages between the second inner electrode segment and the second outer electrode segment to generate a turning current configured to turn the source plasma inwardly toward the Z-pinch axis in the assembly region; and a third power supply configured to apply a third voltage of the at least tw o voltages between the third inner electrode segment and the third outer electrode segment to generate a Z-pinch current configured to flow along the Z-pinch plasma. In some embodiments, the second outer electrode segment extends partly forwardly of the front end of the inner electrode, and the third outer electrode segment extends entirely forwardly of the front end of the inner electrode. In some embodiments, the first power supply is configured to start applying the first voltage before the second power supply is configured to start applying the second voltage, and the second power supply is configured to start applying the second voltage before the third power supply is configured to start applying the third voltage. In some embodiments, a first inner segment insulator interposed between the first and second inner electrode segments is longitudinally aligned with a first outer segment insulator interposed between the first and second outer electrode segments, and a second inner segment insulator interposed between the second and third inner electrode segments is rearwardly disposed with respect to a second outer segment insulator interposed between the second and third outer electrode segments.

[0014] In some embodiments, the Z-pinch plasma includes a radially sheared axial flow. In some embodiments, the Z-pinch plasma is configured to undergo nuclear fusion reactions in response to compression of the Z-pinch plasma. In some embodiments, the Z-pinch plasma is configured to undergo nuclear fusion reactions in response to compression of the Z-pinch plasma. In some embodiments, the inner electrode has a nose cone at the front end thereof, the nose cone forming at least part of the frontmost one of the at least two inner electrode segments. In some embodiments, the number of the at least two inner electrode segments is the same as the number of the at least two outer electrode segments.

[0015] In accordance with another aspect, there is provided a plasma generation method including: providing a source plasma inside an acceleration region defined between an inner electrode and an outer electrode surrounding the inner electrode, wherein the inner electrode extends longitudinally between a front end and a rear end and includes at least two inner electrode segments disposed successively along a Z-pinch axis, wherein the outer electrode extends longitudinally between a front end and a rear end and includes at least two outer electrode segments disposed successively along the Z-pinch axis, and wherein the outer electrode extends forwardly beyond the inner electrode along the Z-pinch axis to define an assembly region adjacent the acceleration region and extending between the front end of the inner electrode and the front end of the outer electrode; and applying at least two voltages between the inner electrode and the outer electrode, each voltage being applied between one of the at least two inner electrode segments and one of the at least two outer electrode segments, wherein the application of the at least two voltages causes the source plasma to flow along the acceleration region and into the assembly region and to be compressed into a Z-pinch plasma along the Z-pinch axis in the assembly region.

[0016] In some embodiments, the plasma generation method further includes providing at least one inner segment insulator longitudinally interleaved with the at least two inner electrode segments, and providing at least one outer segment insulator longitudinally interleaved with the at least two outer electrode segments.

[0017] In some embodiments, the at least two inner electrode segments include a first inner electrode segment; the at least two outer electrode segments include a first outer electrode segment; and providing the source plasma inside the acceleration region includes: supplying a process gas inside the acceleration region; and applying a first voltage of the at least two voltages between the first inner electrode segment and the first outer electrode segment to generate an ionization current configured to ionize the process gas injected inside the acceleration region into the source plasma. In some embodiments, the at least two inner electrode segments further include a second inner electrode segment disposed forwardly of the first inner electrode segment, a third inner electrode segment disposed forwardly of the second inner electrode segment, and a fourth inner electrode segment disposed forwardly of the third inner electrode segment; the at least two outer electrode segments further include a second outer electrode segment disposed forwardly of the first outer electrode segment, a third outer electrode segment disposed forwardly of the second outer electrode segment, and a fourth outer electrode segment disposed forwardly of the fourth outer electrode segment; and applying the at least two voltages between the inner electrode and the outer electrode includes: applying a second voltage of the at least two voltages between the second inner electrode segment and the second outer electrode segment to generate an acceleration current configured to accelerate the source plasma along the acceleration region; applying a third voltage of the at least two voltages between the third inner electrode segment and the third outer electrode segment to generate a turning current configured to turn the source plasma inwardly toward the Z-pinch axis in the assembly region; and applying a fourth voltage of the at least two voltages between the fourth inner electrode segment and the fourth outer electrode segment to generate a Z-pinch current configured to flow along the Z-pinch plasma. In some embodiments, the second outer electrode segment extends entirely rearwardly of the front end of the inner electrode the third outer electrode segment extends partly forwardly of the front end of the inner electrode, and the fourth outer electrode segment extends entirely forwardly of the front end of the inner electrode. In some embodiments, the step of applying the first voltage is initiated before the step of applying the second voltage, the step of applying the second voltage is initiated before the step of applying the third voltage, and the step of applying the third voltage is initiated before the step of applying the fourth voltage.

[0018] In some embodiments, providing the source plasma inside the acceleration region includes generating the source plasma outside the acceleration region, and injecting the source plasma inside the acceleration region. In some embodiments, the at least two inner electrode segments include a first inner electrode segment, a second inner electrode segment disposed forwardly of the first inner electrode segment, and a third inner electrode segment disposed forwardly of the second inner electrode segment; the at least two outer electrode segments include a first outer electrode segment, a second outer electrode segment disposed forwardly of the first outer electrode segment, and a third outer electrode segment disposed forwardly of the second outer electrode segment; and applying the at least two voltages between the inner electrode and the outer electrode further includes: applying a first voltage of the at least two voltages between the first inner electrode segment and the first outer electrode segment to generate an acceleration current configured to accelerate the source plasma along the acceleration region; applying a second voltage of the at least two voltages between the second inner electrode segment and the second outer electrode segment to generate a turning current configured to turn the source plasma inwardly toward the Z-pinch axis in the assembly region; and applying a third voltage of the at least t o voltages between the third inner electrode segment and the third outer electrode segment to generate a Z-pinch current configured to flow along the Z-pinch plasma. In some embodiments, the second outer electrode segment extends partly forwardly of the front end of the inner electrode, and the third outer electrode segment extends entirely forwardly of the front end of the inner electrode. In some embodiments, the step of applying the first voltage is initiated before the step of applying the second voltage, and wherein the step of applying the second voltage is initiated before the step of applying the third voltage.

[0019] In accordance with another aspect, there is provided a plasma generation system including: a plasma confinement device having a longitudinal axis and including an inner electrode and an outer electrode surrounding the inner electrode to define therebetween an acceleration region configured to contain an initial plasma, the outer electrode extending beyond the inner electrode along the longitudinal axis to define an assembly region adjacent the acceleration region, wherein at least one of the inner electrode and the outer electrode includes a plurality of electrode segments including a first electrode segment and a second electrode segment; and a power supply unit including a plurality of power supplies that includes a first power supply configured to apply a first voltage between the inner electrode and the outer electrode via the first electrode segment and a second power supply configured to apply a second voltage between the inner electrode and the outer electrode via the second electrode segment, wherein the application of the first voltage and the second voltage causes the initial plasma to flow along the acceleration region and into the assembly region and to be compressed into a Z-pinch plasma flowing along the longitudinal axis in the assembly region.

[0020] In some embodiments, the plasma confinement device includes a plasma injection port configured to inject the initial plasma into the acceleration region. In such embodiments, the plasma generation system may include a plasma formation and injection device configured to form the initial plasma outside of the acceleration region and to supply the initial plasma into the acceleration region via the plasma injection port. In some embodiments, the plasma confinement device includes a gas injection port configured to inject process gas into the acceleration region. In some variants, the application of at least one of the first voltage and the second voltage causes the process gas injected into the acceleration region to be energized into the initial plasma. In other variants, the plurality of electrode segments includes a third electrode segment, and the plurality of power supplies includes a third power supply configured to apply a third voltage between the inner electrode and the outer electrode via the third electrode segment, wherein the application of the third voltage causes the process gas injected into the acceleration region to be energized into the initial plasma. In some embodiments, the plasma confinement device includes an electrical insulator between the first electrode segment and the second electrode segment. In some embodiments, the Z-pinch plasma has an embedded radially sheared axial flow.

[0021] In accordance with another aspect, there is provided a plasma generation method including: forming or injecting an initial plasma in an acceleration region defined between an inner electrode and an outer electrode surrounding the inner electrode, the outer electrode extending beyond the inner electrode along a longitudinal axis to define an assembly region adjacent the acceleration region, wherein at least one of the inner electrode and the outer electrode includes a plurality of electrode segments including a first electrode segment and a second electrode segment; and applying a first voltage between the inner electrode and the outer electrode via the first electrode segment and a second voltage between the inner electrode and the outer electrode via the second electrode segment to cause the initial plasma to flow along the acceleration region and into the assembly region and to be compressed into a Z-pinch plasma flowing along the longitudinal axis in the assembly region. [0022] In accordance with an aspect, there is provided a plasma confinement device including: an inner electrode; and an outer electrode surrounding the inner electrode to define therebetween an acceleration region configured to contain an initial plasma, the outer electrode extending forwardly beyond the inner electrode to define an assembly region adjacent the acceleration region; wherein at least one of the inner electrode and the outer electrode includes a plurality of electrode segments including a first electrode segment and a second electrode segment; and wherein applying, with a first power supply, a first voltage between the inner electrode and the outer electrode via the first electrode segment and applying, with a second power supply, a second voltage between the inner electrode and the outer electrode via the second electrode segment cause the initial plasma to flow along the acceleration region and into the assembly region and to be compressed into a Z-pinch plasma flowing in the assembly region.

[0023] Other method and process steps may be performed prior, during, or after the steps described herein. The order of one or more steps may also differ, and some of the steps may be omitted, repeated, and/or combined, as the case may be.

[0024] Other objects, features, and advantages of the present description will become more apparent upon reading of the following non-restrictive description of specific embodiments thereof, given by way of example only with reference to the appended drawings. Although specific features described in the above summary and in the detailed description below may be described with respect to specific embodiments or aspects, it should be noted that these specific features may be combined with one another unless stated otherwise.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figs. 1 to 5 are schematic representations of a conventional Z-pinch plasma generation system at five different stages of the Z-pinch formation.

[0026] Fig. 6 is a schematic longitudinal cross-sectional view of a plasma generation system, in accordance with an embodiment.

[0027] Fig. 7 is a schematic longitudinal cross-sectional view of a plasma generation system, in accordance with another embodiment.

[0028] Fig. 8 is a schematic longitudinal cross-sectional view of a plasma generation system, in accordance with another embodiment.

[0029] Fig. 9 is a schematic longitudinal cross-sectional view of a plasma generation system, in accordance with another embodiment. [0030] Fig. 10 is a schematic longitudinal cross-sectional view of a plasma generation system, in accordance with another embodiment.

[0031] Fig. 11 is a schematic longitudinal cross-sectional view of a plasma generation system, in accordance with another embodiment.

[0032] Fig. 12 is a schematic longitudinal cross-sectional view of a plasma generation system, in accordance with another embodiment.

DETAILED DESCRIPTION

[0033] In the present description, similar features in the drawings have been given similar reference numerals. To avoid cluttering certain figures, some elements may not be indicated if they were already identified in a preceding figure. The elements of the drawings are not necessarily depicted to scale, since emphasis is placed on clearly illustrating the elements and structures of the present embodiments. Furthermore, positional descriptors indicating the location and/or orientation of one element with respect to another element are used herein for ease and clarity of description. Unless otherwise indicated, these positional descriptors should be taken in the context of the figures and should not be considered limiting. Such spatially relative terms are intended to encompass different orientations in the use or operation of the present embodiments, in addition to the orientations exemplified in the figures. Furthermore, when a first element is referred to as being “on”, “above”, “below”, “over”, or “under” a second element, the first element can be either directly or indirectly on, above, below, over, or under the second element, respectively, such that one or multiple intervening elements may be disposed between the first element and the second element.

[0034] The terms “a”, “an”, and “one” are defined herein to mean “at least one”, that is, these terms do not exclude a plural number of elements, unless stated otherwise.

[0035] The term “or” is defined herein to mean “and/or”, unless stated otherwise.

[0036] The expressions “at least one of X, Y, and Z” and “one or more of X, Y, and Z”, and variants thereof, are understood to include X alone, Y alone, and Z alone, as well as any combination of X, Y, and Z.

[0037] The terms “first”, “second”, “third”, “fourth”, and the like in the description and in the claims are used only for more clearly distinguishing between similar elements, and not necessarily for describing a particular sequential or chronological order.

[0038] Terms such as “substantially”, “generally”, and “about”, which modify a value, condition, or characteristic of a feature of an exemplary embodiment, should be understood to mean that the value, condition, or characteristic is defined within tolerances that are acceptable for the proper operation of this exemplary embodiment for its intended application or that fall within an acceptable range of experimental error. In particular, the term “about” generally refers to a range of numbers that one skilled in the art would consider equivalent to the stated value (e.g., having the same or an equivalent function or result). In some instances, the term “about” means a variation of ±10% of the stated value. It is noted that all numeric values used herein are assumed to be modified by the term “about”, unless stated otherwise. The term “between” as used herein to refer to a range of numbers or values defined by endpoints is intended to include both endpoints, unless stated otherwise.

[0039] The term “based on” as used herein is intended to mean “based at least in part on”, whether directly or indirectly, and to encompass both “based solely on” and “based partly on”. In particular, the term “based on” may also be understood as meaning “depending on”, “representative of’, “indicative of’, “associated with”, “relating to”, and the like.

[0040] The terms “match”, “matching”, and “matched” refer herein to a condition in which two elements are either the same or within some predetermined tolerance of each other. That is, these terms are meant to encompass not only “exactly” or “identically” matching the two elements, but also “substantially”, “approximately”, or “subjectively” matching the two elements, as well as providing a higher or best match among a plurality of matching possibilities.

[0041] The terms “connected” and “coupled”, and derivatives and variants thereof, refer herein to any connection or coupling, either direct or indirect, between two or more elements, unless stated otherwise. For example, the connection or coupling between elements may be mechanical, optical, electrical, magnetic, thermal, chemical, logical, fluidic, operational, or any combination thereof.

[0042] The term “concurrently” refers herein to two or more processes that occur during coincident or overlapping time periods. The term “concurrently” does not necessarily imply complete synchronicity and encompasses various scenarios including time-coincident or simultaneous occurrence of two processes; occurrence of a first process that both begins and ends during the duration of a second process; and occurrence of a first process that begins during the duration of a second process, but ends after the completion of the second process.

[0043] The present description generally relates to plasma generation systems and methods using segmented electrodes for providing control over the plasma generation process. The techniques disclosed herein may be used in various fields and applications, including fusion power generation, neutron and high-energy photon generation, materials processing, and space propulsion.

[0044] The plasma generation system 100’ includes a plasma confinement device 102’ and a power supply unit 104’ configured to supply power to the plasma confinement device 102’. The plasma confinement device 102’ includes an inner electrode 116’ and an outer electrode 118’. The inner electrode 116’ and the outer electrode 118’ form a coaxial electrode arrangement extending along a longitudinal Z-pinch axis 114’. In the illustrated configuration, the outer electrode 118’ extends longitudinally beyond the inner electrode 116’. The annular volume extending between the inner electrode 116’ and the outer electrode 118’ defines a plasma acceleration region 120’, while the cylindrical volume surrounded by the outer electrode 118’ and extending beyond the inner electrode 116’ defines a Z-pinch assembly region 130’. The plasma acceleration region 120’ and the Z- pinch assembly region 130’ define a reaction chamber 182’ of the plasma confinement device 102’. The formation of a Z-pinch plasma involves injecting neutral gas in the acceleration region 120’ (Fig. 1), and applying, using the power supply unit 104’, an electric potential difference between the inner electrode 116’ and the outer electrode 118’ (Fig. 2). The neutral gas can be injected into the acceleration region 120’ via one or more gas injection ports 140’ of the plasma confinement device 102’ (e g., formed through the peripheral surface of the outer electrode 118’), the one or more gas injection ports 140’ being connected to a gas supply system including a neutral gas source (not shown). The power supply unit 104’ can include a high-voltage capacitor bank and a switch. The electric potential difference applied between the inner electrode 116’ and the outer electrode 118’ is configured to ionize the neutral gas, resulting in the formation of an annular column or washer of plasma in the acceleration region 120’ . The plasma column allows electric current to flow radially therethrough between the inner and outer electrodes 116’, 118’ (Fig. 2). The electric current that flows axially along the inner electrode 116’ generates an azimuthal magnetic field in the acceleration region 120’ (Fig. 3).

[0045] The interaction between the radial electric current flowing in the plasma column and the azimuthal magnetic field produces a Lorentz force in the axial direction that pushes and accelerates the plasma column axially forward along the acceleration region 120’ (Fig. 3) until the plasma column reaches the entrance of the assembly region 130’ and the Z-pinch formation begins (Fig. 4). In the assembly region 130’, the direction of the Lorentz force changes from longitudinal to radially inward, which makes the plasma column collapse inwardly toward the Z-pinch axis 114’ to complete the formation of the Z-pinch plasma (Fig. 5). The axial current flowing in the Z-pinch plasma generates an azimuthal magnetic field that exerts an inward magnetic pressure and an inward magnetic tension, which radially compress the Z-pinch plasma against the outward plasma pressure until an equilibrium is established. In this configuration, the Z-pinch plasma can continue to form and move along the assembly region 130’ for as long as neutral gas is supplied and ionized in the acceleration region 120’. In Figs. 1 to 5, the plasma confinement device 102’ includes a plasma exit port 184’ configured to allow part of the Z-pinch plasma to exit the plasma confinement device 102’, so as to avoid a stagnation point in the plasma flow that could create instabilities.

[0046] By increasing the axial current to compress the Z-pinch plasma to sufficiently high density and temperature, fusion reactions can be achieved within the pinch, resulting in an exothermic energy release. In many applications, fusion reactions release their energy in the form of neutrons. A commonly used fusion reaction is the deuterium-tritium reaction, or D-T reaction, in which the fusion of one deuterium nucleus and one tritium nucleus produces one alpha particle and one neutron. Being chargeless, neutrons can escape from the magnetically confined plasma pinch and transfer their kinetic energy into thermal energy after they exit the confinement region. This thermal energy can be converted into electricity, for example, by transferring the heat generated to a working fluid used by a heat engine for generating electrical energy. The remaining fusion products have kinetic energy that can contribute more energy to the fusion process.

[0047] Conventional Z-pinch configurations are unstable due to the presence of magnetohydrodynamic (MHD) instabilities. A challenge in Z-pinch fusion research is devising ways of improving the control of instabilities to keep Z-pinch plasmas confined long enough to sustain ongoing fusion reactions. Techniques such as close fitting walls, axial magnetic fields, and pressure profile control have been proposed, with mitigated results. Recent advances have demonstrated that sheared plasma flows — that is, plasma flows with a radius-dependent axial velocity — can provide a promising stabilization approach to achieving and sustaining fusion conditions in Z-pinch configurations. For example, the velocity at the center of the Z-pinch plasma may range from about 20 km/s to about 150 km/s, while the velocity at the edge of the Z-pinch plasma may range from about 80 km/s to 150 km/s or may be as low as -20 km/s to 20 km/s. One of the keys to unlocking the potential of sheared-flow-stabilized Z-pinch fusion devices as these devices are scaled up in power input, and thus in power output, is to mitigate, circumvent, or otherwise control instabilities, turbulence, heat transfer, and other factors limiting plasma lifetime. This is because once the reaction becomes unstable, the pinch ceases, neutron production stops, and power generation shuts down. Researchers have theorized that fusion conditions resulting in viable net power output that can be met at high power input are achievable when the flow shear exceeds a certain threshold above which the Z-pinch is stable, this threshold depending on the magnetic field strength and the plasma density. It is appreciated that the theory, instrumentation, implementation, and operation of conventional sheared-flow-stabilized Z-pinch plasma confinement devices are generally known in the art and need not be described in detail herein other than to facilitate an understanding of the present techniques. Reference is made in this regard to international patent application PCT US2018/019364 (published as WO 2018/156860) as well as the following doctoral dissertation: Golingo, Raymond, Formation of a Sheared Flow Z-Pinch (University of Washington, 2003). The contents of these two documents are incorporated herein by reference in their entirety.

[0048] Sheared-flow-stabilized Z-pinch plasmas generally operate in a quasi-steady state that is reached after a start-up or formation process. In the quasi-steady state, the total plasma current includes a number of current components or sets having different roles and properties and being located at different positions along the acceleration region and the assembly region. For example, in the case of neutral gas injection, the total plasma current may include, from the upstream end to the downstream end of the plasma confinement device, the following currents components (see also Figs. 6 to 12 ): an ionization current j_ion that ionizes the neutral gas injected in the acceleration region into the source plasma; an acceleration current j_accel that accelerates the source plasma along the acceleration region as result of an axial j_accel ^x B force; a tuming/compression current j_turn that turns the plasma exiting the acceleration region to exert a radially inward force that entrains and compresses the plasma to form the Z-pinch plasma in the assembly region; and a Z-pinch current j_pinch that flows through the Z-pinch plasma between the inner electrode and the outer electrode. In conventional Z-pinch configurations, these various current components result from the application of a voltage between a single-segment inner electrode and a single-segment outer electrode using a single power supply. These conventional configurations may suffer from suboptimal current distribution among the different current components, which typically tends to undesirably favor the more upstream current components (e.g., the ionization and acceleration currents) to the detriment of the more downstream current components (e.g., the compression/tuming and Z-pinch currents). In some applications, this suboptimal current distribution may result in the Z-pinch current being insufficient to compress the Z-pinch plasma to fusion conditions.

[0049] Some embodiments of the techniques disclosed herein aim to address or at least mitigate the issue of suboptimal current distribution by providing a plasma confinement device having a segmented electrode configuration. In such a configuration, the inner electrode and the outer electrode of the plasma confinement device include multiple electrode segments. The multiple electrode segments have different positions along the acceleration region and the assembly region and are connected to different, independently controlled power supplies. In some embodiments, a segmented electrode configuration can allow for a better distribution of the total plasma current among its different contributions and, ultimately, for a higher fusion energy gain factor.

[0050] Referring to Fig. 6, there is illustrated a schematic longitudinal cross-sectional view of a plasma generation system 100, in accordance with an embodiment. The plasma generation system 100 can be used for generating fusion reactions, for example, neutronic fusion reactions. The plasma generation system 100 of Fig. 6 generally includes a plasma confinement device 102, a power supply unit 104, and a process gas supply unit 106. The process gas supply unit 106 is configured to supply a process gas 108 to the plasma confinement device 102. The power supply unit 104 is configured to supply electric power to the plasma confinement device 102 to ionize or otherwise energize the process gas 108 into a source or initial plasma 110 and to accelerate and compress the source plasma 110 into a Z-pinch plasma 112 and to sustain the Z-pinch plasma 112. In some applications, the plasma generation system 100 is configured to compress and heat the Z-pinch plasma 112 sufficiently to reach fusion conditions, that is, plasma temperature and density conditions at which fusion reactions occur inside the Z-pinch plasma 112. In such applications, the energy produced by the fusion reactions, which typically involve the generation of neutrons, exceeds the input energy required to establish fusion conditions.

[0051] More detail regarding the structure, configuration, and operation of these components and other possible components of the plasma generation system 100 are provided below. It is appreciated that Fig. 6 is a simplified schematic representation that illustrates certain features and components of the plasma generation system 100, such that additional features and components that may be useful or necessary for its practical operation may not be specifically depicted, and likewise for Figs. 7 to 12 described below. Non-limiting examples of such additional features and components can include, to name a few, power supplies, electrical connections, gas sources, gas supply lines (e.g., conduits, such as pipes or tubes), pressure and flow control devices (e.g., pumps, valves, regulators, restrictors), operation monitoring and diagnostic devices (e.g., sensors), processors and controllers, and other types of hardware and equipment.

[0052] In Fig. 6, the plasma confinement device 102 extends along a longitudinal axis 114, or Z-pinch axis, along which the Z-pinch plasma 112 is formed and sustained. The term “Z-pinch plasma” broadly refers herein to a plasma that has an electric current flowing substantially along the longitudinal or axial direction Z of a cylindrical coordinate system. The axial electrical current generates an azimuthal magnetic field that radially compresses, or pinches, the plasma by the Lorentz force. It is appreciated that in some instances, terms such as “Z-pinch”, “zeta pinch”, “plasma pinch”, “pinch”, “plasma arc” may be used interchangeably with the term “Z-pinch plasma”.

[0053] The plasma confinement device 102 includes an inner electrode 116 and an outer electrode 118 surrounding the inner electrode 116 to define therebetween a plasma acceleration region 120 configured to contain the source plasma 110. In the illustrated embodiment, the inner electrode 116 and the outer electrode 118 each have an elongated configuration along the Z-pinch axis 114. The inner electrode 116 extends longitudinally between a front end 122 and a rear end 124, and the outer electrode 118 extends longitudinally a front end 126 and a rear end 128. The outer electrode 118 extends forwardly beyond the inner electrode 116 along the Z-pinch axis 114 to define a Z-pinch assembly region 130 adjacent the acceleration region 120 and extending between the front end 122 of the inner electrode 116 and the front end 126 of the outer electrode 118. The acceleration region 120 and the assembly region 130 define a reaction chamber 182 of the plasma confinement device 102.

[0054] In the illustrated arrangement, the inner electrode 116 and the outer electrode 118 both have a substantially cylindrical configuration, with a circular cross-section transverse to the Z-pinch axis 114, and the outer electrode 118 encloses the inner electrode 116 in a coaxial arrangement with respect to the Z-pinch axis 114. However, various other electrode configurations may be used in other embodiments. Non-limiting examples include, to name a few, non-coaxial arrangements, non-circularly symmetric transverse cross-sections, three-electrode arrangements, and the like. In some embodiments, the inner electrode 116 may have a length ranging from about 25 cm to about one or a few meters and a radius ranging from about 2 cm to about 1 m, while the outer electrode 118 may have a length ranging from about 50 cm to about 6 m, a radius ranging from about 6 cm to about 2 m or more, and a wall thickness ranging from about 6 mm to about 12 mm, although other electrode dimensions may be used in other embodiments. Depending on the application, the inner electrode may have a full or hollow configuration. The inner electrode 116 and the outer electrode 118 may each be made of any suitable electrically conductive material, such as various metals and metal alloys. Non-limiting examples include, to name a few, tungsten-coated copper and graphite. It is appreciated that the size, shape, composition, structure, and arrangement of the inner electrode 116 and the outer electrode 118 can be varied depending on the application.

[0055] The plasma confinement device 102 can also include an electrode insulator 132 disposed between the inner electrode 116 and the outer electrode 118. The electrode insulator 132 is configured to provide electrical insulation between the inner electrode 116 and the outer electrode 118 so as to prevent or help prevent unwanted charge buildup and other undesirable electrical phenomena that could adversely affect the operation of the plasma generation system 100. In the illustrated embodiment, the electrode insulator 132 has an annular cross-sectional shape and is disposed near the rear ends 124, 128 of the inner and outer electrodes 116, 118. The electrode insulator 132 may be made of any suitable electrically insulating material. Non-limiting examples of such possible materials include glass, ceramic, and glass-ceramic materials. More specific examples of possible materials include, to name a few, alumina, boron nitride, borosilicate glass, porcelain, and MACOR® (a machinable boro- aluminosilicate glass-ceramic by Corning Inc.). It is appreciated that the electrode insulator 132 may be of varying sizes, shapes, compositions, locations, and configurations depending on the application.

[0056] Referring still to Fig. 6, the acceleration region 120 has a substantially annular cross-sectional shape defined by the cross-sectional shapes of the inner and outer electrodes 116, 118. The acceleration region 120 is configured to receive the process gas 108 from the process gas supply unit 106. The process gas 108 can be any suitable gas or gas mixture capable of being energized into the source plasma 110 by the power supplied by the power supply unit 104. Depending on the application, the process gas 108 can be a neutral gas or gas mixture, or a weakly ionized gas or gas mixture. The process gas 108 may contain fusion reactants. For example, in some embodiments, the process gas 108 may be deuterium gas (D-D reaction), a gas mixture containing deuterium and tritium (D-T reaction), a gas mixture containing deuterium and helium-3 (D-³He reaction), or a gas mixture containing protons and boron (p -ⁿB reaction). Other mixtures may include hydrogen or helium. The acceleration region 120 is also configured to allow the source plasma 110 thus formed to flow therealong and into the assembly region 130. In some embodiments, the acceleration region 120 may have a length ranging from about 25 cm to about 1.5 m and an annular thickness ranging from about 2 cm to about 1 m, although other dimensions may be used in other embodiments. [0057] The process gas supply unit 106 is configured to supply the process gas 108 into the acceleration region 120 for the process gas 108 to be energized into the source plasma 110. The process gas supply unit 106 can include or be coupled to a process gas source 134 configured to store the process gas 108. The process gas source 134 may be embodied by a gas storage tank or any suitable pressurized gas dispensing container. The process gas supply unit 106 may also include a process gas supply line 136 (e.g., including gas conduits or channels) configured to convey the process gas 108 from the process gas source 134 to the acceleration region 120 of the plasma confinement device 102. The process gas supply unit 106 may further include a process gas supply valve 138 or other flow control devices configured to control a flow of the process gas 108 along the process gas supply line 136, from the process gas source 134 to the acceleration region 120. The process gas supply valve 138 may be embodied by a variety of electrically actuated valves, such as a solenoid valve. Other flow control devices (not shown), such as pumps, regulators, and restrictors, may be provided to control the process gas flow rate and pressure along the process gas supply line 136. [0058] To allow the injection of the process gas 108 into the acceleration region 120, the plasma confinement device 102 can include one or more process gas injection ports 140 connected to the process gas supply line 136 and leading into the acceleration region 120. For example, in the illustrated embodiment, the plasma confinement device 102 includes two process gas injection ports 140 formed through the outer electrode 118 at opposite azimuthal positions but the same longitudinal position with respect to the Z-pinch axis 114. Depending on the application, the one or more process gas injection ports 140 may be formed only through the inner electrode 116, only through the outer electrode 118, through both the inner electrode 116 and the outer electrode 118, or at any other suitable locations of the plasma confinement device 102. The process gas injection configuration and the number and arrangement of the process gas injection ports 140 can be varied depending on the application. [0059] In some embodiments, the source plasma 110 formed from the process gas 108 may have the following properties and parameters: an electron temperature ranging from about 1 eV to about 100 eV, an ion temperature ranging from about 1 eV to about 100 eV, an electron density ranging from about 10¹³ cm⁻³ to about 10¹⁶ cm⁻³, an ion density ranging from about 10¹³ cm⁻³ to about 10¹⁶ cm⁻³, and a degree of ionization ranging from about 50% to about 100%. Depending on the application, the source plasma 110 may be magnetized or unmagnetized. [0060] Referring still to Fig.6, the assembly region 130 has a substantially circular cross-sectional shape defined by the cross-sectional shape of the portion of the outer electrode 118 that projects forwardly beyond the front end 122 of the inner electrode 116. In the illustrated embodiment, the front end 122 of the inner electrode 116 is flat, and the front end 126 of the outer electrode 118 defines a front end wall of the plasma confinement device 102. However, non-flat geometries (e.g., half- spherical, conical, tapered, either concave or convex) for the front end 122 of the inner electrode 116 and/or the front end 126 of the outer electrode 118 are possible in other embodiments, as depicted in Figs.7 and 10. The assembly region 130 is configured to sustain the Z-pinch plasma 112 along the Z- pinch axis 114 between the front end 122 of the inner electrode 116 and the front end 126 of the outer electrode 118. In some embodiments, the assembly region 130 may have a length ranging from about 25 cm to about 3 m, although other dimensions may be used in other embodiments. In some embodiments, the plasma confinement device 102 may include a plasma exit port 184 configured to allow part of the Z-pinch plasma 112 to exit the plasma confinement device 102, so as to avoid a stagnation point in the plasma flow that could create instabilities and destroy the Z-pinch plasma 112. In the illustrated embodiment, the plasma exit port 184 is provided as a hole formed on the Z-pinch axis 114 at the front end wall of the outer electrode 118. In other embodiments, the plasma exit port 184 may provided at other locations of the plasma confinement device 102, for example, through the peripheral wall of the outer electrode 118. In yet other embodiments, a plurality of plasma exit ports may be provided. [0061] In some embodiments, the Z-pinch plasma 112 may have the following properties and parameters: a plasma radius ranging from about 0.1 mm to about 5 mm, a magnetic field ranging from about 1 T to about 8 T, an electron temperature ranging from about 500 eV to about 10 keV, an ion temperature ranging from about 500 eV to about 10 keV, an electron density ranging from about 10¹⁷ cm⁻³ to about 10²⁰ cm⁻³, an ion density ranging from about 10¹⁷ cm⁻³ to about 10²⁰ cm⁻³, and a stable lifetime exceeding 10 µs (e.g., up to 1 ms). These values are provided by way of example, so that other values may be used in other embodiments. Depending on the application, the Z-pinch plasma 112 may or may not be sheared flow stabilized. As noted above, the plasma generation system 100 may be configured to compress the Z-pinch plasma 112 sufficiently to reach fusion conditions. In such embodiments, the fusion reactions produced and sustained inside the Z-pinch plasma 112 can lead to the production of neutrons, whose energy can be converted into electricity in fusion power applications. [0062] In the embodiment illustrated in Fig.6, the plasma confinement device 102 has a segmented electrode arrangement. More specifically, the inner electrode 116 and the outer electrode 118 both include a plurality of electrode segments, namely a first, second, third and fourth inner electrode segments 142₁-142₄ for the inner electrode 116 and a first, second, and third outer electrode segments 144₁-144₄ for the outer electrode 118. The four inner electrode segments 142₁-142₄ are disposed successively along the Z-pinch axis 114, with the second inner electrode segment 142₂ disposed forwardly of the first inner electrode segment 142₁, the third inner electrode segment 142₃ disposed forwardly of the second inner electrode segment 142₂, and the fourth inner electrode segment 142₄ disposed forwardly of the third inner electrode segment 142₃. The four outer electrode segments 144₁-144₄ are disposed successively along the Z-pinch axis 114, with the second outer electrode segment 144₂ disposed forwardly of the first outer electrode segment 144₁, the third outer electrode segment 144₃ disposed forwardly of the second outer electrode segment 144₂, and the fourth outer electrode segment 144₄ disposed forwardly of the third outer electrode segment 144₃. The first and second outer electrode segments 144₁-144₂ extend entirely rearwardly of the front end 122 of the inner electrode 116, the third outer electrode segment 144₃ extends partly forwardly of the front end 122 of the inner electrode 116, and the fourth outer electrode segment 144₄ extends entirely forwardly of the front end 122 of the inner electrode 116. In other embodiments, the number of inner electrode segments may be equal to two or three or be larger than four, and likewise for the number of outer electrode segments. Depending on the application, the number of inner electrode segments and the number of outer electrode segments may or may not be the same. In general, it is appreciated that the size, shape, composition, structure, and arrangement of the inner electrode segments 142₁-142₄ and the outer electrode segments 144₁-144₄ can be varied depending on the application. In the illustrated embodiment, the process gas injection ports 140 are formed through the first outer electrode segment 144₁, but other configurations are possible in other embodiments. [0063] Referring still to Fig.6, the plasma confinement device 102 also includes at least one inner segment insulator 146₁-146₃ longitudinally interleaved with and configured to provide electrical insulation between the at least two inner electrode segments 142₁-142₄, and at least one outer segment insulator 148₁-148₃ longitudinally interleaved with and configured to provide electrical insulation between the at least two outer electrode segments 144₁-144₄. More specifically, the at least one inner segment insulator 146₁-146₃ includes a first inner segment insulator 146₁ longitudinally interposed between the first inner electrode segment 142₁ and the second inner electrode segment 142₂, a second inner segment insulator 146₂ longitudinally interposed between the second inner electrode segment 142₂ and the third inner electrode segment 142₃, and a third inner segment insulator 146₃ longitudinally interposed between the third inner electrode segment 142₃ and the fourth inner electrode segment 1424. The at least one outer segment insulator 1481-1483 includes a first outer segment insulator 148₁ longitudinally interposed between the first outer electrode segment 144₁ and the second outer electrode segment 144₂, a second outer segment insulator 148₂ longitudinally interposed between the second outer electrode segment 144₂ and the third outer electrode segment 144₃, and a third outer segment insulator 148₃ longitudinally interposed between the third outer electrode segment 144₃ and the fourth outer electrode segment 144₄. In the illustrated embodiment, the inner segment insulators 146₁-146₃ and the outer segment insulators 148₁-148₃ each have an annular cross-sectional shape defined by the shape of the inner electrode 116 and the shape of the outer electrode 118, respectively. [0064] The provision of the inner segment insulators 146₁-146₃ and the outer segment insulators 148₁- 148₃ can ensure or help ensure the integrity and performance characteristics of the inner electrode segments 142₁-142₄ and the outer electrode segments 144₁-144₄ during operation of the plasma generation system 100. The inner segment insulators 146₁-146₃ and the outer segment insulators 148₁- 148₃ may be configured to prevent or reduce the likelihood of arcing among the inner electrode segments 142₁-142₄ and among the outer electrode segments 144₁-144₄, and other types of electrical damage, failure, and interference. The inner segment insulators 146₁-146₃ and the outer segment insulators 148₁-148₃ may be made of any suitable electrically insulating material. Non-limiting examples of such possible materials include glass, ceramic, and glass-ceramic materials. More specific examples of possible materials include, to name a few, alumina, boron nitride, borosilicate glass, porcelain, and MACOR®. In some embodiments, the inner segment insulators 1461-1463 and the outer segment insulators 148₁-148₃ may advantageously be made of a material having a high dielectric strength, a high mechanical strength, a good machinability, good thermal insulating properties, or any combination thereof. Depending on the application, the inner segment insulators 146₁-146₃ and the outer segment insulators 148₁-148₃ may be of varying numbers, sizes, shapes, compositions, locations, and configurations. Furthermore, different segment insulators 146₁-146₃, 148₁-148₃ may or may not be identical to one another. In some embodiments, electrical insulation between the inner electrode segments 1421-1424 and between the outer electrode segments 1441-1444 may be provided not by segment insulators 146₁-146₃, 148₁-148₃ (i.e., solid insulating breaks) but by vacuum or gas gaps. [0065] Referring still to Fig.6, the power supply unit 104 is electrically connected to the inner electrode 116 and the outer electrode 118 via appropriate electrical connections. In the illustrated embodiment, the power supply unit 104 includes a first power supply 150₁, a second power supply 150₂, a third power supply 150₃, and a fourth power supply 150₄. The term “power supply” refers herein to any device or combination of devices configured to supply electrical power into a form usable by another device or combination of devices. The first power supply 150₁ is configured to apply a first voltage between the first inner electrode segment 142₁ and the first outer electrode segment 144₁. The second power supply 1502 is configured to apply a second voltage between the second inner electrode segment 142₂ and the second outer electrode segment 144₂. The third power supply 150₃ is configured to apply a third voltage between the third inner electrode segment 142₃ and the third outer electrode segment 144₃. The fourth power supply 150₄ is configured to apply a fourth voltage between the fourth inner electrode segment 142₄ and the fourth outer electrode segment 144₄. The inner electrode 116 may have a hollow configuration to provide a path for connecting each one of the inner electrode segments 142₁-142₄ to the respective one of the power supplies 150₁-150₄. In some embodiments, the inner electrode segments 142₁-142₄ are electrically biased (either positively or negatively) and the outer electrode segments 144₁-144₄ are electrically grounded. However, the opposite configuration may also be used, in which the inner electrode segments 142₁-142₄ are electrically grounded and the outer electrode segments 144₁-144₄ are electrically biased (either positively or negatively). It is appreciated that various biasing and circuit arrangements, which may or may not be the same for different segment pairs, can be used depending on the application. [0066] In some embodiments, each power supply 150₁-150₄ may be a pulsed-DC power supply and may include an energy source (e.g., a capacitor bank), a switch (e.g., a spark gap, an ignitron, or a semiconductor switch), and a pulse shaping network (including, e.g., inductors, resistors, diodes, and the like). In some embodiments, the voltage applied by each power supply 1501-1504 may range from about 1 kV to about 40 kV, although other voltage values may be used in other embodiments Depending on the application, the power supplies 150₁-150₄ may be voltage-controlled or current-controlled. Other suitable types of power supplies may be used in other embodiments, including DC and AC power supplies. Non-limiting examples include, to name a few, DC grids, voltage source converters, and homopolar generators. [0067] In some embodiments, the process of applying any of the four voltages by the power supplies 150₁-150₄ is initiated after initiating the process of injecting the process gas 108 into the acceleration region 120 by the process gas supply unit 106. For example, in some embodiments, the gas injection process can be initiated from about 100 µs to about 4000 µs prior to the process of applying any of the four voltages. However, in other embodiments, the process of applying the four voltages can be initiated before or at the same time as initiating the process of injecting the process gas 108 into the acceleration region 120. [0068] The application of the four voltages causes the process gas 108 injected into the acceleration region 120 to be ionized into the source plasma 110 and causes the source plasma 110 thus formed to flow along the acceleration region 120, turn into the assembly region 130, and be compressed into the Z-pinch plasma 112. It is appreciated that the operation of the power supplies 150₁-150₄ may be selected in view of favoring these different processes. To this end, the four power supplies 150₁-150₄ may be operated independently from one another to provide individual control over various parameters of the four voltages, including their magnitudes, waveforms, start times, end times, and durations. Depending on the application, any of these parameters may or may not be identical among the four voltages. For example, in some embodiments, each voltage may be different during start-up than it is neutron production. Furthermore, the four voltages may or may not be applied over simultaneous time periods. [0069] In the illustrated embodiment, each one of the four voltages applied by the four power supplies 150₁-150₄ is configured to generate and control a respective one of the four currents introduced above, that is, the ionization current j_ion, the acceleration current j_accel, the turning current j_turn, and the Z-pinch current j_pinch. The first voltage applied between the first inner electrode segment 142₁ and the first outer electrode segment 1441 is configured to generate the ionization current jion that ionizes the process gas 108 injected inside the acceleration region 120 so as form the source plasma 110. The second voltage applied between the second inner electrode segment 142₂ and the second outer electrode segment 144₂ is configured to generate the acceleration current j_accel that accelerates the source plasma 110 along the acceleration region 120. The third voltage applied between the third inner electrode segment 142₃ and the third outer electrode segment 144₃ is configured to generate the turning current j_turn that turns the source plasma 110 inwardly toward the Z-pinch axis 114 in the assembly region 130. The fourth voltage applied between the fourth inner electrode segment 142₄ and the fourth outer electrode segment 144₄ is configured to generate the Z-pinch current j_pinch configured to flow along and sustain the Z-pinch plasma 112. The four voltages can be individually adjusted to achieve better control over the ionization current j_ion, the acceleration current j_accel, the turning current j_turn, and the Z- pinch current jpinch. As a result, the processes of (i) ionizing the process gas 108 into the source plasma 110, (ii) accelerating the source plasma 110 along the acceleration region 120, (iii) turning and compressing the source plasma 110 radially inwardly upon entering the assembly region 130, and (iv) forming and sustaining the Z-pinch plasma 112 in the assembly region 130 can be substantially decoupled from one another. Decoupling these processes can in turn provide enhanced control over the Z-pinch parameters and properties (e.g., plasma density, temperature, velocity, magnetic field, and the like). It is appreciated that the ionization current j_ion need not be controlled solely by the first voltage, and likewise for the other currents jaccel, jturn, and jpinch and their associated voltages. For example, in some embodiments, the ionization current j_ion may be predominantly controlled by the first voltage but marginally controlled by the second voltage, or the acceleration current j_accel may be predominantly controlled by the second voltage but marginally controlled by the first and third voltages. [0070] In some embodiments, the application of each voltage can be initiated at different times in accordance with a predetermined sequence. For example, the first power supply 150₁ may be configured to start applying the first voltage before the second power supply 150₂ is configured to start applying the second voltage, the second power supply 150₂ may be configured to start applying the second voltage before the third power supply 150₃ is configured to start applying the third voltage, and the third power supply 1503 may be configured to start applying the third voltage before the fourth power supply 150₄ is configured to start applying the fourth voltage. In some embodiments, each voltage can be applied as soon as or slightly after the process gas 108 (in the case of the first voltage) or the source plasma 110 (in the case of the second, third, and fourth voltages) enters the section of the reaction chamber 182 enclosed by the corresponding pair of inner and outer electrodes segments. For example, if the injection of the process gas 108 inside the acceleration region 120 starts at time t₀, the first voltage can be applied starting at time t₁ for a duration Δt₁, where start time t₁ can be from about 0 µs to about 4000 µs after t₀ and Δt₁ can range from about 40 µs to about 1000 µs. The application of the first voltage generates an ionization current j_ion that ionizes the process gas 108 into the source plasma 110. The second voltage can be applied as soon as or slightly after the source plasma 110 begins to form. For example, the second voltage can be applied starting at time t₂ for a duration Δt₂, where start time t₂ can be from about 1 µs to about 15 µs after t₁ and Δt₂ can range from about 35 µs to about 900 µs. The application of the second voltage generates an acceleration current j_accel that pushes the source plasma 110 forward along the acceleration region 120. The third voltage can be applied as soon as or slightly before the source plasma 110 reaches the front end 122 of the inner electrode 116. For example, the third voltage can be applied starting at time t₃ for a duration Δt₃, where start time t₃ can be from about 10 µs to about 30 µs after t₁ and Δt₃ can range from about 20 µs to about 900 µs. The application of the third voltage generates a turning current j_turn that moves the source plasma 110 radially inwardly toward the Z-pinch axis 114 in the assembly region 130. The fourth voltage can be applied as soon as or slightly after the Z-pinch plasma 112 begins to form. For example, the fourth voltage can be applied starting at time t4 for a duration Δt4, where start time t4 can be from about 20 µs to about 40 µs after t1 and Δt₄ can range from about 10 µs to about 900 µs. It is appreciated that for a time period beginning at start time t₄ and continuing until one of the voltages reaches its end time, the four voltages are applied concurrently to the reaction chamber 182. It is appreciated that this example of activation sequence for the four voltages is provided by way of example only, and that various other activation sequences are contemplated by the present techniques. For instance, in some embodiments, the application of the four voltages can be initiated simultaneously. [0071] In the embodiment illustrated in Fig.6, the plasma confinement device 102 includes four inner electrode segments 142₁-142₄ and four outer electrode segments 144₁-144₄, and the power supply unit 104 includes four power supplies 150₁-150₄. However, in other embodiments, these numbers may be varied for a particular application and need not be identical to one another. For example, in some embodiments, the plasma confinement device 102 may include m inner electrode segments and n outer electrode segments, where m ≥ 2, n ≥ 2, and m and n may or may not be the same, and the power supply unit 104 may include a number of power supplies equal to max(m, n). For example, in some embodiments, m and n can range from two to ten, although larger values of m and n can be used in other embodiments. [0072] Referring to Fig.7, there is illustrated a schematic longitudinal cross-sectional view of another embodiment of a plasma generation system 100. This embodiment shares several features with the embodiment of Fig.6, which will not be described again other than to highlight differences between them. In contrast to the embodiment of Fig.6, in Fig.7, the inner electrode 116 has a nose cone 186 at the front end 122 thereof that tapers down to a forward tip that couples with the Z-pinch plasma 112 on the Z-pinch axis 114. Non-limiting examples for the composition of the nose cone 186 include, to name a few, tungsten, copper, tungsten-coated copper, and graphite. The nose cone 186 forms at least part of the frontmost one of the inner electrode segments, which in Fig.7 is the fourth inner electrode segment 142₄. As in Fig.6, each pair of inner and outer electrode segments in the arrangement of Fig.7 has its own power supply to allow substantially independent control over a different current component of the total plasma current: first pair of inner and outer electrode segments 142₁-144₁ and first power supply 150₁ for the ionization current j_ion; second pair of inner and outer electrode segments 142₂-144₂ and second power supply 150₂ for the acceleration current j_accel; third pair of inner and outer electrode segments 142₃-144₃ and third power supply 150₃ for the turning current j_turn; and fourth pair of inner and outer electrode segments 142₄-144₄ and fourth power supply 150₄ for the Z-pinch current j_pinch. [0073] Referring to Fig.8, there is illustrated a schematic longitudinal cross-sectional view of another embodiment of a plasma generation system 100. This embodiment shares several features with the embodiments of Figs.6 and 7, which will not be described again other than to highlight differences between them. In contrast to the embodiment of Figs.6 and 7, in Fig.8, the inner electrode 116 is segmented into three inner electrode segments 142₁-142₃ disposed successively along the Z-pinch axis 114, and the outer electrode 118 is segmented into three outer electrode segments 144₁-144₃ disposed successively along the Z-pinch axis 114. The three inner electrode segments 142₁-142₃ includes a first inner electrode segment 142₁, a second inner electrode segment 142₂ disposed forwardly of the first inner electrode segment 142₁, and a third inner electrode segment 142₃ disposed forwardly of the second inner electrode segment 142₂. The three outer electrode segments 144₁-144₃ includes a first outer electrode segment 144₁, a second outer electrode segment 144₂ disposed forwardly of the first outer electrode segment 144₁, and a third outer electrode segment 144₃ disposed forwardly of the second outer electrode segment 144₂. The first and second outer electrode segments 144₁-144₂ extend entirely rearwardly of the front end 122 of the inner electrode 116, and the third outer electrode segment 144₃ extends partly forwardly of the front end 122 of the inner electrode 116. In Fig.8, the plasma confinement device 102 includes two inner segment insulator 146₁-146₂ longitudinally interleaved with and configured to provide electrical insulation between the three inner electrode segments 142₁-142₃, and two outer segment insulators 148₁-148₂ longitudinally interleaved with and configured to provide electrical insulation between the three outer electrode segments 144₁-144₃. More specifically, the two segment insulators 146₁-146₂ include a first inner segment insulator 146₁ longitudinally interposed between the first inner electrode segment 1421 and the second inner electrode segment 1422, and a second inner segment insulator 146₂ longitudinally interposed between the second inner electrode segment 142₂ and the third inner electrode segment 142₃, while the two outer segment insulator 148₁- 148₂ include a first outer segment insulator 148₁ longitudinally interposed between the first outer electrode segment 144₁ and the second outer electrode segment 144₂ and a second outer segment insulator 148₂ longitudinally interposed between the second outer electrode segment 144₂ and the third outer electrode segment 144₃. [0074] In the embodiment of Fig.8, the power supply unit 104 includes a first power supply 150₁, a second power supply 150₂, and a third power supply 150₃. The first power supply 150₁ is configured to apply a first voltage between the first inner electrode segment 142₁ and the first outer electrode segment 144₁, the second power supply 150₂ is configured to apply a second voltage between the second inner electrode segment 142₂ and the second outer electrode segment 144₂, and the third power supply 150₃ is configured to apply a third voltage between the third inner electrode segment 142₃ and the third outer electrode segment 144₃. In some embodiments, the process of applying the three voltages by the power supplies 150₁-150₃ is initiated after initiating the process of injecting the process gas 108 into the acceleration region 120 by the process gas supply unit 106, but this is not a requirement. The application of the three voltages causes the process gas 108 injected into the acceleration region 120 to be ionized into the source plasma 110 and causes the source plasma 110 thus formed to flow along the acceleration region 120, turn into the assembly region 130, and be compressed into the Z-pinch plasma 112. In the illustrated embodiment, the first voltage applied between the first inner electrode segment 142₁ and the first outer electrode segment 144₁ is configured to generate an ionization current j_ion that ionizes the process gas 108 injected inside the acceleration region 120 so as form the source plasma 110. The second voltage is configured to generate an acceleration current j_accel that accelerates the source plasma 110 along the acceleration region 120. The third voltage is configured to generate both a turning current j_turn that turns the source plasma 110 inwardly toward the Z-pinch axis 114 in the assembly region 130 and a Z-pinch current j_pinch configured to flow along and sustain the Z-pinch plasma 112. [0075] The three voltages can be individually adjusted to achieve better control over the formation and sustainment of the Z-pinch plasma 114 by substantially decoupling (i) the ionization current j_ion, (ii) the acceleration current j_accel, and (iii) the turning current j_turn, and the Z-pinch current j_pinch from one another. In some embodiments, the application of each voltage can be initiated at different times in accordance with a predetermined sequence. For example, the first power supply 150₁ may be configured to start applying the first voltage before the second power supply 150₂ is configured to start applying the second voltage, and the second power supply 150₂ may be configured to start applying the second voltage before the third power supply 150₃ is configured to start applying the third voltage. In some embodiments, each voltage can be applied as soon as or slightly after the process gas 108 (in the case of the first voltage) or the source plasma 110 (in the case of the second and third voltages) enters the section of the reaction chamber 182 enclosed by the corresponding pair of inner and outer electrodes segments. For example, if the injection of the process gas 108 inside the acceleration region 120 starts at time t₀, the first voltage can be applied starting at time t₁ for a duration Δt₁, where start time t₁ can be from about 0 µs to about 4000 µs after t₀ and Δt₁ can range from about 40 µs to about 1000 µs, the second voltage can be applied starting at time t₂ for a duration Δt₂, where start time t₂ can be from about 1 µs to about 15 µs after t₁ and Δt₂ can range from about 35 µs to about 900 µs, and the third voltage can be applied starting at time t₃ for a duration Δt₃, where start time t₃ can be from about 10 µs to about 30 µs after t₁ and Δt₃ can range from about 20 µs to about 900 µs. It is appreciated that for a time period beginning at start time t₃ and continuing until one of the voltages reaches its end time, the three voltages are applied concurrently to the reaction chamber 182. It is appreciated that this example of activation sequence for the three voltages is provided by way of example only, and that various other activation sequences are contemplated by the present techniques. [0076] Referring to Fig.9, there is illustrated a schematic longitudinal cross-sectional view of another embodiment of a plasma generation system 100. This embodiment shares several features with the embodiments of Figs.6 to 8, which will not be described again other than to highlight differences between them. In contrast to the embodiment of Figs.6 to 8, in Fig.9, the inner electrode 116 is segmented into two inner electrode segments 142₁-142₂ disposed successively along the Z-pinch axis 114, and the outer electrode 118 is segmented into two outer electrode segments 144₁-144₂ disposed successively along the Z-pinch axis 114. The two inner electrode segments 142₁-142₂ includes a first inner electrode segment 142₁ and a second inner electrode segment 142₂ disposed forwardly of the first inner electrode segment 142₁. The two outer electrode segments 144₁-144₂ includes a first outer electrode segment 144₁ and a second outer electrode segment 144₂ disposed forwardly of the first outer electrode segment 144₁. The first outer electrode segment 144₁ extends entirely rearwardly of the front end 122 of the inner electrode 116, and the second outer electrode segment 144₂ extends partly forwardly of the front end 122 of the inner electrode 116. In Fig.8, the plasma confinement device 102 includes one inner segment insulator 146 longitudinally interleaved with and configured to provide electrical insulation between the two inner electrode segments 142₁-142₂, and one outer segment insulator 148 longitudinally interleaved with and configured to provide electrical insulation between the two outer electrode segments 144₁-144₂. [0077] In the embodiment of Fig.9, the power supply unit 104 includes a first power supply 150₁ configured to apply a first voltage between the first inner electrode segment 142₁ and the first outer electrode segment 144₁, and a second power supply 150₂ configured to apply a second voltage between the second inner electrode segment 142₂ and the second outer electrode segment 144₂. In some embodiments, the process of applying the two voltages by the power supplies 150₁-150₂ is initiated after initiating the process of injecting the process gas 108 into the acceleration region 120 by the process gas supply unit 106, but this is not a requirement. The application of the two voltages causes the process gas 108 injected into the acceleration region 120 to be ionized into the source plasma 110 and causes the source plasma 110 thus formed to flow along the acceleration region 120, turn into the assembly region 130, and be compressed into the Z-pinch plasma 112. In the illustrated embodiment, the first voltage is configured to generate both (i) an ionization current j_ion that ionizes the process gas 108 injected inside the acceleration region 120 so as form the source plasma 110, and (ii) an acceleration current j_accel that accelerates the source plasma 110 along the acceleration region 120, while the second voltage is configured to generate both (i) a turning current j_turn that turns the source plasma 110 inwardly toward the Z-pinch axis 114 in the assembly region 130, and (ii) a Z-pinch current j_pinch configured to flow along and sustain the Z-pinch plasma 112. [0078] The two voltages can be individually adjusted to achieve better control over the formation and sustainment of the Z-pinch plasma 112 by substantially decoupling the application of the ionization current j_ion, and the acceleration current j_accel from the application of the turning current j_turn and the Z- pinch current j_pinch. In some embodiments, the application of each voltage can be initiated at different times in accordance with a predetermined sequence. For example, the first power supply 1501 may be configured to start applying the first voltage before the second power supply 150₂ is configured to start applying the second voltage. In some embodiments, the first voltage can be applied as soon as or slightly after the process gas 108 has been injected inside the acceleration region 120, and the second voltage can be applied around the time that the source plasma 110 reaches the end of the acceleration region 120. For example, if the injection of the process gas 108 inside the acceleration region 120 starts at time t₀, the first voltage can be applied starting at time t₁ for a duration Δt₁, where start time t₁ can be from about 0 µs to about 4000 µs after t₀ and Δt₁ can range from about 40 µs to about 1000 µs, and the second voltage can be applied starting at time t₂ for a duration Δt₂, where start time t₂ can be from about 10 µs to about 30 µs after t₁ and Δt₂ can range from about 20 µs to about 900 µs. It is appreciated that for a time period beginning at start time t₂ and continuing until one of the two voltages reaches its end time, both voltages are applied concurrently to the reaction chamber 182. It is appreciated that this example of activation sequence for the two voltages is provided by way of example only, and that various other activation sequences are contemplated by the present techniques. [0079] Referring to Fig.10, there is illustrated a schematic longitudinal cross-sectional view of another embodiment of a plasma generation system 100. This embodiment shares several features with the embodiment of Fig.9, which will not be described again other than to highlight differences between them. In contrast to the embodiment of Fig.9, in Fig.10, the first inner electrode segment 142₁ is shaped as a cylindrical shell disposed coaxially around the second inner electrode segment 142₂. The second inner electrode segment 142₂ is shaped as a cylinder with an enlarged head that projects forwardly outside the first inner electrode segment 142₁ to define a nose cone 186 which tapers down to a forward tip that couples with the Z-pinch plasma 112 on the Z-pinch axis 114. As in Fig.9, the power supply unit 104 in Fig.10 includes a first power supply 1501 configured to apply a first voltage between the first inner electrode segment 142₁ and the first outer electrode segment 144₁ of the outer electrode 118, and a second power supply 150₂ configured to apply a second voltage between the second inner electrode segment 142₂ and the second outer electrode 144₂ of the outer electrode 118. In this arrangement, the first voltage can be used to predominantly control the ionization current j_ion and the acceleration current j_accel, and the second voltage applied can be used to predominantly control the turning current j_turn and the Z-pinch current j_pinch. [0080] Referring to Fig.11, there is illustrated a schematic longitudinal cross-sectional view of another embodiment of a plasma generation system 100. This embodiment shares several features with the embodiments of Figs.6 to 10, which will not be described again other than to highlight differences between them. In contrast to the embodiments of Figs.6 to 10, in Fig.9, the source plasma 110 is formed outside the acceleration region 120 of the plasma confinement device 102, and the externally formed source plasma 110 is injected or otherwise coupled into the acceleration region 120 where it is accelerated and compressed into the Z-pinch plasma 112. The injection an externally and already formed source plasma 110 inside the acceleration region 120 can allow the plasma formation process to be controlled largely independently from the plasma acceleration and compression process. This independent control can in turn provide enhanced control over the Z-pinch parameters and properties (e.g., plasma density, temperature, velocity, stability, lifetime, magnetic field, and the like). Fusion conditions can therefore be established in the Z-pinch plasma 112 as a result of two largely decoupled and separately controlled processes. In particular, controlled plasma injection can allow for a stable Z- pinch plasma to provide higher fusion power gain sustained over longer periods of time, with reduced or better controlled power losses and other energy inefficiencies. Non-limiting examples of plasma generation systems and methods that use such or similar plasma injection techniques are described in co-assigned International Patent Application No. PCT/US2021/062830, filed December 10, 2021, the contents of which are incorporated herein by reference in their entirety. [0081] The plasma generation system 100 of Fig.11 generally includes a plasma confinement device 102, a plasma formation and injection device 152, and a power supply unit 104. The plasma confinement device 102 extends along a Z-pinch axis 114 and includes an inner electrode 116 and an outer electrode 118 surrounding the inner electrode 116 to define therebetween a plasma acceleration region 120. The inner electrode 116 and the outer electrode 118 each have an elongated configuration along the Z-pinch axis 114. The outer electrode 118 extends forwardly beyond the inner electrode 116 to define a Z-pinch assembly region 130 adjacent the acceleration region 120. The plasma confinement device 102 also includes one or more plasma injection ports 154 formed through the outer electrode 118. The plasma formation and injection device 152 is configured to generate a source plasma 110 outside the acceleration region 120 and to introduce, inject, or otherwise couple the source plasma 110 inside the acceleration region 120 via the one or more plasma injection ports 154 formed through the plasma confinement device. The power supply unit 104 is configured to supply electric power to the plasma confinement device 102 to cause the source plasma 110 to be accelerated and compressed into a Z-pinch plasma 112 and to sustain the Z-pinch plasma 112. [0082] In the embodiment of Fig.11, the inner electrode 116 includes three inner electrode segments 142₁-142₃ disposed successively along the Z-pinch axis 114 and longitudinally interleaved with two inner segment insulators 146₁-146₂. The second inner electrode segment 142₂ is disposed forwardly of the first inner electrode segment 142₁, and the third inner electrode segment 142₃ is disposed forwardly of the second inner electrode segment 142₂. The outer electrode 118 includes three outer electrode segments 144₁-144₃ disposed successively along the Z-pinch axis 114 and longitudinally interleaved with two outer segment insulators 148₁-148₂. The second outer electrode segment 144₂ is disposed forwardly of the first outer electrode segment 144₁, and the third outer electrode segment 144₃ is disposed forwardly of the second outer electrode segment 144₂. The first outer electrode segment 144₁ extends entirely rearwardly of the front end 122 of the inner electrode 116, the second outer electrode segment 144₂ extends partly forwardly of the front end 122 of the inner electrode 116, and the third outer electrode segment 144₃ extends entirely forwardly of the front end 122 of the inner electrode 116. In other embodiments, the number of inner electrode segments may be equal to two or larger than three, and likewise for the number of outer electrode segments. Depending on the application, the number of inner electrode segments and the number of outer electrode segments may or may not be the same. In general, it is appreciated that the size, shape, composition, structure, and arrangement of the inner electrode segments 142₁-142₃ and the outer electrode segments 144₁-144₃ can be varied depending on the application. In the illustrated embodiment, the plasma injection ports 154 are formed through the first outer electrode segment 144₁, but other configurations are possible in other embodiments. The power supply unit 104 includes three power supplies 150₁-150₃, each of which coupled to a corresponding pair of the inner and outer electrode segments 142₁-142₃, 144₁-144₃. [0083] Referring still to Fig.11, the plasma formation and injection device 152 includes two distinct plasma sources or generators 156, each of which coupled to a corresponding one of the plasma injection ports 154, so that each plasma generator 156 contributes a respective portion of the source plasma 110 injected into the acceleration region 120. However, in other embodiments, the number of plasma generators 156 and the number plasma injection ports 154 may be neither equal to each other nor equal to two. It is appreciated that many plasma formation and generation techniques exist, notably in fusion power applications, and may be used in the embodiments disclosed herein to form the source plasma 110 with desired or required properties. In particular, the theory, instrumentation, implementation, and operation of plasma sources and are generally known in the art and need not be described in detail herein other than to facilitate an understanding of the present techniques. [0084] In Fig.11, each of the two plasma generators 156 of the plasma formation and injection device 152 is configured as a coaxial plasma gun. It is appreciated, however, that other types of electromagnetic plasma generators can be used in other embodiments. Coaxial plasma guns and other electromagnetic plasma generators generally operate by using the electric field generated by a high- voltage power supply to energize a gas into a plasma, and by relying on the Lorentz force to propel the plasma toward an outlet of the plasma gun. In Fig.11, each coaxial plasma generator 156 has a longitudinal plasma formation axis 158 and includes an inner electrode 160 and an outer electrode 162 disposed around the inner electrode 160 in a coaxial arrangement with respect to the plasma formation axis 158. In addition, the outer electrode 162 projects longitudinally beyond the inner electrode 160 and terminates at the plasma injection port 154. In some embodiments, the inner electrode 160 may have a length ranging from about 75 mm to about 250 mm and a radius ranging from about 2 mm to about 7.5 mm, while the outer electrode 162 may have a length ranging from about 75 mm to about 275 mm, a radius ranging from about 12 mm to about 25 mm, and a wall thickness ranging from about 2.5 mm to about 7.5 mm, although other electrode dimensions may be used in other embodiments. The annular volume extending between the inner electrode 160 and the outer electrode 162 defines a plasma formation region 164 configured to receive a process gas 108 (e.g., a neutral gas or another plasma precursor gas) for the process gas 108 to be energized into the source plasma 110. The cylindrical volume surrounded by the outer electrode 162 and extending longitudinally beyond the front end of the inner electrode 160 defines a plasma transport channel 166 of the plasma generator 156, which extends from the plasma formation region 164 to the plasma injection port 154 along the plasma formation axis 158. [0085] As noted with respect to the embodiment illustrated in Fig.6, the process gas 108 can be any suitable neutral or weakly ionized gas or gas mixture capable of being energized into the source plasma 110 by the plasma generator 156. For example, in some embodiments, the process gas 108 may be deuterium gas (D-D reaction), a gas mixture containing deuterium and tritium (D-T reaction), a gas mixture containing deuterium and helium-3 (D-³He reaction), or a gas mixture containing protons and boron (p⁺-¹¹B reaction). Other mixtures may include hydrogen or helium. The source plasma 110 may be formed by supplying the process gas 108 to the plasma formation region 164 and by applying a voltage between the inner and outer electrodes 160, 162 to ionize or otherwise energize the process gas 108 into the source plasma 110. For this purpose, each plasma generator 156 of the plasma formation and injection device 152 can include or be coupled to a process gas supply unit 106 and a plasma formation power supply 168. Depending on the application, the operation of introducing the process gas 108 into the plasma formation region 164 can be initiated before, at the same time as, or after initiating the operation of activating the plasma formation power supply 168 to apply the voltage between the inner electrode 160 and the outer electrode 162. [0086] Each process gas supply unit 106 may include or be coupled to a process gas source 134 configured to store the process gas 108. The process gas source 134 may be embodied by a gas storage tank or any suitable pressurized dispensing container. The process gas supply unit 106 may also include a process gas supply line 136 configured to provide fluid communication between the process gas source 134 and the plasma formation region 164 of each plasma generator 156. The process gas supply unit 106 may further include a process gas supply valve 138 configured to control a flow of the process gas 108 along the process gas supply line 136, from the process gas source 134 to the plasma formation region 164 of each plasma generator 156. The process gas supply valve 138 may be embodied by a variety of electrically actuated valves, such as a solenoid valve. Various process gas injection configurations may be used depending on the application. For example, in some embodiments, a single gas source may be configured to supply process gas to multiple plasma generators.

[0087] Referring still to Fig. 11, each plasma formation power supply 168 is connected to the inner electrode 160 and the outer electrode 162 of its corresponding plasma generator 156 via appropriate electrical connections. Depending on the application, the plasma formation power supplies 168 may or may not be identical to each other. In the illustrated embodiment, each plasma formation power supply 168 includes a capacitor bank and a switch, although other suitable types of power supplies may be used in other embodiments (e.g., flywheel power supplies). Each plasma formation power supply 168 is configured to apply a voltage between the inner and outer electrodes 160, 162 to generate an ionizing electric field across the plasma formation region 164. The ionizing electric field is configured to ionize and break down the process gas 108, thereby forming the source plasma 110. In some embodiments, the voltage applied between the inner and outer electrodes 160, 162 may range from about 750 V to about 5 kV, although other voltage values may be used in other embodiments. It is appreciated that the configuration and the operation of the plasma formation power supplies 168 may be adjusted to favor the breakdown of the process gas 108 and control the parameters of the source plasma 110. It is also appreciated that in other embodiments, the plasma formation and injection device 152 may use other types of plasma sources and plasma formation techniques to form the source plasma 110. Non-limiting examples of such possible plasma sources include, to name a few, gas injected washer plasma guns; plasma thrusters, for example, Hall effect thrusters and MHD thrusters; if the source plasma 110 is magnetized, high-power helicon plasma sources; RF plasma sources; plasma torches; and laser-based plasma sources.

[0088] The portion of the source plasma 110 formed by each plasma generator 156 is transported along the plasma transport channel 166 from the plasma formation region 164 to the corresponding plasma injection port 154 for injection into the acceleration region 120. It is appreciated that the portions of the source plasma 110 formed by the two plasma generators 156 may have the same or different plasma compositions or parameters. Transport of the source plasma 110 along the plasma transport channel 166 can be achieved by or as a result of the axial momentum imparted to the source plasma 110 as it leaves the plasma formation region 164. In particular, the formation of the source plasma 110 can result in a radial electric current and an azimuthal magnetic field. The interaction between the radial electric current and the azimuthal magnetic field produces an axial Lorentz force that pushes and accelerates the source plasma 110 forward along the plasma formation region 164 and into the plasma transport channel 166 toward the plasma injection port 154. The plasma injection ports 154 can be used to control the rate of introduction of the source plasma 110 into the acceleration region 120 and the plasma properties, which in turn can provide better control over the Z-pinch lifetime and properties. The size, the shape, the longitudinal and azimuthal positions, the plasma injection angle (i.e., the plane encompassing the Z-pinch axis 114 and the plasma formation axis 158; and the plasma injection angle (i.e., the angle between the Z-pinch axis 114 and the plasma formation axis 158), and other parameters of the plasma injection ports 154 may be varied in accordance with the application. It is appreciated that the embodiment of Fig.11 is provided by way of example only, and that various other plasma injection configurations are contemplated for use in the present techniques. For example, in some embodiments, it could be envisioned to inject the source plasma 110 inside the acceleration region 120 via one or more plasma injection ports formed through in the inner electrode 116. [0089] Referring still to Fig.11, the process of applying the three voltages by the power supplies 150₁- 150₄ can initiated after initiating the process of injecting the source plasma 110 into the acceleration region 120 by the plasma formation and injection device 152, but this is not a requirement. The application of the three voltages causes the source plasma 110 injected into the acceleration region 120 to flow along the acceleration region 120, turn into the assembly region 130, and be compressed into the Z-pinch plasma 112. It is appreciated that the operation of the power supplies 150₁-150₃ may be selected in view of favoring these different processes. To this end, the three power supplies 150₁-150₃ may be operated independently from one another to provide individual control over various parameters of the three voltages, including their magnitudes, waveforms, start times, end times, and durations. In the illustrated embodiment, the first voltage is configured to generate an acceleration current j_accel that accelerates the source plasma 110 along the acceleration region 120, the second voltage is configured to generate a turning current j_turn that turns the source plasma 110 inwardly toward the Z-pinch axis 114 in the assembly region 130, and the third voltage is configured to generate a Z-pinch current j_pinch configured to flow along and sustain the Z-pinch plasma 112. In this arrangement, the processes of (i) accelerating the source plasma 110 along the acceleration region 120, (ii) turning and compressing the source plasma 110 radially inwardly upon entering the assembly region 130, and (iii) forming and sustaining the Z-pinch plasma 112 in the assembly region 130 can advantageously be substantially decoupled from one another. [0090] In some embodiments, the application of each voltage can be initiated at different times in accordance with a predetermined sequence. For example, the first power supply 1501 may be configured to start applying the first voltage before the second power supply 150₂ is configured to start applying the second voltage, and the second power supply 150₂ may be configured to start applying the second voltage before the third power supply 150₃ is configured to start applying the third voltage. In some embodiments, each voltage can be applied as soon as or slightly after the source plasma 110 enters the section of the reaction chamber 182 enclosed by the corresponding pair of inner and outer electrodes segments. For example, if the injection of the source plasma 110 inside the acceleration region 120 starts at time t₀, the first voltage can be applied starting at time t₁ for a duration Δt₁, where start time t₁ can be from about 0 µs to about 100 µs after t₀ and Δt₁ can range from about 40 µs to about 1000 µs. The application of the first voltage generates an acceleration current j_accel that pushes the source plasma 110 forward along the acceleration region 120. The second voltage can be applied as soon as or slightly before the source plasma 110 reaches the front end 122 of the inner electrode 116. For example, the second voltage can be applied starting at time t₂ for a duration Δt₂, where start time t₂ can be from about 10 µs to about 30 µs after t₁ and Δt₂ can range from about 20 µs to about 900 µs. The application of the third voltage generates a turning current j_turn that moves the source plasma 110 radially inwardly toward the Z-pinch axis 114 in the assembly region 130. The third voltage can be applied as soon as or slightly after the Z-pinch plasma 112 begins to form. For example, the third voltage can be applied starting at time t3 for a duration Δt3, where start time t3 can be from about 20 µs to about 40 µs after t1 and Δt₃ can range from about 10 µs to about 900 µs. It is appreciated that for a time period beginning at start time t₃ and continuing until one of the voltages reaches its end time, the three voltages are applied concurrently to the reaction chamber 182. It is appreciated that this example of activation sequence for the three voltages is provided by way of example only, and that various other activation sequences are contemplated by the present techniques. [0091] Referring to Fig.12, there is illustrated a schematic longitudinal cross-sectional view of another embodiment of a plasma generation system 100. This embodiment shares several features with the embodiment of Fig 11, which will not be described again other than to highlight differences between them. In contrast to the embodiment of Fig.11, in Fig.12, the inner electrode 116 is segmented into two inner electrode segments 142₁-142₂ disposed successively along the Z-pinch axis 114, and the outer electrode 118 is segmented into two outer electrode segments 144₁-144₂ disposed successively along the Z-pinch axis 114. The two inner electrode segments 142₁-142₂ includes a first inner electrode segment 142₁ and a second inner electrode segment 142₂ disposed forwardly of the first inner electrode segment 142₁, while the two outer electrode segments 144₁-144₂ includes a first outer electrode segment 144₁ and a second outer electrode segment 144₂ disposed forwardly of the first outer electrode segment 1441. The first outer electrode segment 1441 extends entirely rearwardly of the front end 122 of the inner electrode 116, and the second outer electrode segment 144₂ extends partly forwardly of the front end 122 of the inner electrode 116. In Fig.12, the plasma confinement device 102 includes one inner segment insulator 146 longitudinally interleaved with and configured to provide electrical insulation between the two inner electrode segments 142₁-142₂, and one outer segment insulator 148 longitudinally interleaved with and configured to provide electrical insulation between the two outer electrode segments 144₁-144₂. [0092] In the embodiment of Fig.12, the power supply unit 104 includes a first power supply 150₁ configured to apply a first voltage between the first inner electrode segment 142₁ and the first outer electrode segment 144₁, and a second power supply 150₂ configured to apply a second voltage between the second inner electrode segment 142₂ and the second outer electrode segment 144₂. In some embodiments, the process of applying the two voltages by the power supplies 150₁-150₂ is initiated after initiating the process of injecting the source plasma 110 into the acceleration region 120 by the plasma formation and injection device 152, but this is not a requirement. The application of the two voltages causes the source plasma 110 thus injected to flow along the acceleration region 120, turn into the assembly region 130, and be compressed into the Z-pinch plasma 112. In the illustrated embodiment, the first voltage is configured to generate an acceleration current j_accel that accelerates the source plasma 110 along the acceleration region 120, while the second voltage is configured to generate both a turning current j_turn that turns the source plasma 110 inwardly toward the Z-pinch axis 114 in the assembly region 130, and a Z-pinch current jpinch configured to flow along and sustain the Z-pinch plasma 112. [0093] The two voltages can be individually adjusted to achieve better control over the formation and sustainment of the Z-pinch plasma 112 by substantially decoupling the application of the acceleration current j_accel from the application of the turning current j_turn and the Z-pinch current j_pinch. In some embodiments, the application of each voltage can be initiated at different times in accordance with a predetermined sequence. For example, the first power supply 150₁ may be configured to start applying the first voltage before the second power supply 150₂ is configured to start applying the second voltage. In some embodiments, the first voltage can be applied as soon as or slightly after the source plasma 110 has been injected inside the acceleration region 120, and the second voltage can be applied around the time that the source plasma 110 reaches the end of the acceleration region 120. For example, if the injection of the source plasma 110 inside the acceleration region 120 starts at time t₀, the first voltage can be applied starting at time t₁ for a duration Δt₁, where start time t₁ can be from about 0 µs to about 100 µs after t₀ and Δt₁ can range from about 40 µs to about 1000 µs, and the second voltage can be applied starting at time t₂ for a duration Δt₂, where start time t₂ can be from about 10 µs to about 40 µs after t₁ and Δt₂ can range from about 10 µs to about 1000 µs. It is appreciated that for a time period beginning at start time t2 and continuing until one of the two voltages reaches its end time, both voltages are applied concurrently to the reaction chamber 182. It is appreciated that this example of activation sequence for the two voltages is provided by way of example only, and that various other activation sequences are contemplated by the present techniques. [0094] In some embodiments, including those illustrated in Figs.6 to 12, the plasma generation system 100 can include a vacuum system 170. The vacuum system 170 includes a vacuum chamber 172, for example, a stainless steel pressure vessel. The vacuum chamber 172 is configured to house at least partially various components of the plasma generation system 100, including at least part of the inner electrode 116 and the outer electrode 118 of the plasma confinement device 102. The vacuum chamber 172 may include vacuum ports 174 formed therethrough to allow the process gas 108 (see Figs.6 to 10) or the source plasma 110 (see Figs.11 and 12) to be introduced into the acceleration region 120 of the plasma confinement device 102. The vacuum system 170 may also include a pressure control unit (not shown) configured to control the operating pressure inside the vacuum chamber 172. In some embodiments, the pressure inside the vacuum chamber 172 may range from about 10⁻⁹ Torr to about 20 Torr, although other ranges of pressure may be used in other embodiments. [0095] Returning to Fig.6, the plasma generation system 100 can further include a control and processing device 176, which is configured to control, monitor, and coordinate the functions and operation of various components of the plasma generation system 100, as well as various temperature, pressure, and power conditions. Non-limiting examples of components that can be controlled by the control and processing device 176 include the power supply unit 104, the process gas supply unit 106, and the plasma formation power supplies 168. The control and processing device 176 may be implemented in hardware, software, firmware, or any combination thereof, and be connected to various components of the plasma generation system 100 via wired and/or wireless communication links configured to send and/or receive various types of signals, such as timing and control signals, measurement signals, and data signals. The control and processing device 176 may be controlled by direct user input and/or by programmed instructions, and may include an operating system for controlling and managing various functions of the plasma generation system 100. Depending on the application, the control and processing device 176 may be fully or partly integrated with, or physically separate from, the other hardware components of the plasma generation system 100. The control and processing device 176 can include a processor 178 and a memory 180. For simplicity, a control and processing device 176 is only depicted in Fig.6. However, it is appreciated that any of the embodiments of Figs.7 to 12 can include a control and processing device such as the one depicted in Fig.6 and described herein. [0096] The processor 178 may be able to execute computer programs, also generally known as commands, instructions, functions, processes, software codes, executables, applications, and the like. It should be noted that although the processor 178 in Fig.7 is depicted as a single entity for illustrative purposes, the term “processor” should not be construed as being limited to a single processor, and the processor 178 may represent the processing functionality of a plurality of devices operating in coordination. The processor 178 may include or be part of a computer; a microprocessor; a microcontroller; a coprocessor; a central processing unit (CPU); an image signal processor (ISP); a digital signal processor (DSP) running on a system on a chip (SoC); a single-board computer (SBC); a dedicated graphics processing unit (GPU); a special-purpose programmable logic device embodied in hardware device, such as, for example, a field-programmable gate array (FPGA) or an application- specific integrated circuit (ASIC); and/or other mechanisms configured to electronically process information and to operate collectively as a processor.

[0097] The memory 180, which may also be referred to as a “computer readable storage medium” is capable of storing computer programs and other data to be retrieved by the processor 178. In the present description, the terms “computer readable storage medium” and “computer readable memory” are intended to refer to a non-transitory and tangible computer product that can store and communicate executable instructions for the implementation of various steps of the methods disclosed herein. The computer readable memory may be any computer data storage device or assembly of such devices, including a random-access memory (RAM) device; a dynamic RAM device; a read-only memory (ROM) device; a magnetic storage device, such as a hard disk drive; an optical storage device, such as an optical disc drive; a solid-state storage device, such as a solid-state drive and a flash memory drive; and/or any other non-transitory memory technologies. A plurality of such storage devices may be provided. The computer readable memory may be associated with, coupled to, or included in a computer or processor configured to execute instructions contained in a computer program stored in the computer readable memory and relating to various functions associated with the computer.

[0098] The plasma generation system 100 may also include one or more user interface devices (not shown) operatively connected to the control and processing device 176 to allow the input of commands and queries to the plasma generation system 100, as well as present the outcomes of the commands and queries. The user interface devices may include input devices (e.g., a touch screen, a keypad, a keyboard, a mouse, a switch, and the like) and output devices (e.g., a display screen, a printer, visual and audible indicators and alerts, and the like).

[0099] In accordance with another aspect, there is provided a plasma generation method. The method can be implemented in a plasma generation system such as the ones depicted in Figs. 6 to 12, or another suitable plasma generation system. The method can include a step of providing a source plasma inside an acceleration region defined between an inner electrode and an outer electrode surrounding the inner electrode. The inner electrode extends longitudinally between a front end and a rear end and including at least two inner electrode segments disposed successively along a Z-pinch axis. The outer electrode extends longitudinally between a front end and a rear end and includes at least two outer electrode segments disposed successively along the Z-pinch axis. The outer electrode the outer electrode also extends forwardly beyond the inner electrode along the Z-pinch axis to define an assembly region adjacent the acceleration region and extending between the front end of the inner electrode and the front end of the outer electrode. The method can also include a step of applying at least two voltages between the inner electrode and the outer electrode, each voltage being applied between one of the at least two inner electrode segments and one of the at least two outer electrode segments. The application of the at least two voltages causes the source plasma to flow along the acceleration region and into the assembly region and to be compressed into a Z-pinch plasma along the Z-pinch axis in the assembly region.

[0100] Numerous modifications could be made to the embodiments described above without departing from the scope of the appended claims.

Claims

1. A plasma generation system comprising: a plasma confinement device extending along a longitudinal Z-pinch axis and comprising: an inner electrode extending longitudinally between a front end and a rear end, the inner electrode comprising at least two inner electrode segments disposed successively along the Z-pinch axis; and an outer electrode extending longitudinally between a front end and a rear end, the outer electrode comprising at least two outer electrode segments disposed successively along the Z-pinch axis, the outer electrode surrounding the inner electrode to define therebetween an acceleration region configured to contain a source plasma, the outer electrode extending forwardly beyond the inner electrode along the Z-pinch axis to define an assembly region adjacent the acceleration region and extending between the front end of the inner electrode and the front end of the outer electrode; and a power supply unit comprising at least two power supplies, each power supply being configured to apply a respective one of at least two voltages between one of the at least two inner electrode segments and one of the at least two outer electrode segments, wherein the application of the at least two voltages causes the source plasma to flow along the acceleration region and into the assembly region and to be compressed into a Z-pinch plasma along the Z-pinch axis in the assembly region.

2. The plasma generation system of claim 1, further comprising: at least one inner segment insulator longitudinally interleaved with the at least two inner electrode segments; and at least one outer segment insulator longitudinally interleaved with the at least two outer electrode segments.

3. The plasma generation system of claim 1 or 2, further comprising a process gas supply unit configured to supply a process gas inside the acceleration region via a process gas injection port formed in the plasma confinement device, and wherein: the at least two inner electrode segments comprise a first inner electrode segment; the at least two outer electrode segments comprise a first outer electrode segment; and the at least two power supplies comprise a first power supply configured to apply a first voltage of the at least two voltages between the first inner electrode segment and the first outer electrode segment to generate an ionization current configured to ionize the process gas injected inside the acceleration region into the source plasma.

4. The plasma generation system of claim 3, wherein the gas injection port is formed through the inner electrode or through the outer electrode.

5. The plasma generation system of claim 3 or 4, wherein the process gas comprises deuterium, tritium, hydrogen, or helium, or any combination thereof

6. The plasma generation system of any one of claims 3 to 5, wherein: the at least two inner electrode segments further comprise a second inner electrode segment disposed forwardly of the first inner electrode segment; the at least two outer electrode segments further comprise a second outer electrode segment disposed forwardly of the first outer electrode segment; the first power supply is further configured to apply the first voltage between the first inner electrode segment and the first outer electrode segment to generate an acceleration current configured to accelerate the source plasma along the acceleration region; and the at least two power supplies further comprise a second power supply configured to apply a second voltage of the at least two voltages between the second inner electrode segment and the second outer electrode segment to generate a turning current configured to turn the source plasma inwardly toward the Z-pinch axis in the assembly region and a Z-pinch current configured to flow along the Z-pinch plasma.

7. The plasma generation system of claim 6, wherein the second outer electrode segment extends partly forwardly of the front end of the inner electrode.

8. The plasma generation system of claim 6 or 7, wherein the first power supply is configured to start applying the first voltage before the second power supply is configured to start applying the second voltage.

9. The plasma generation system of any one of claims 3 to 5, wherein: the at least two inner electrode segments further comprise a second inner electrode segment disposed forwardly of the first inner electrode segment, and a third inner electrode segment disposed forwardly of the second inner electrode segment; the at least two outer electrode segments further comprise a second outer electrode segment disposed forwardly of the first outer electrode segment, and a third outer electrode segment disposed forwardly of the second outer electrode segment; and the at least two power supplies further comprise: a second power supply configured to apply a second voltage of the at least two voltages between the second inner electrode segment and the second outer electrode segment to generate an acceleration current configured to accelerate the source plasma along the acceleration region; and a third power supply configured to apply a third voltage of the at least two voltages between the third inner electrode segment and the third outer electrode segment to generate a turning current configured to turn the source plasma inwardly toward the Z-pinch axis in the assembly region and a Z-pinch current configured to flow along the Z-pinch plasma.

10. The plasma generation system of claim 9, wherein the second outer electrode segment extends entirely rearwardly of the front end of the inner electrode, and wherein the third outer electrode segment extends partly forwardly of the front end of the inner electrode.

11. The plasma generation system of claim 9 or 10, wherein the first power supply is configured to start applying the first voltage before the second power supply is configured to start applying the second voltage, and wherein the second power supply is configured to start applying the second voltage before the third power supply is configured to start applying the third voltage.

12. The plasma generation system any one of claims 3 to 5, wherein: the at least two inner electrode segments further comprise a second inner electrode segment disposed forwardly of the first inner electrode segment, a third inner electrode segment disposed forwardly of the second inner electrode segment, and a fourth inner electrode segment disposed forwardly of the third inner electrode segment; the at least two outer electrode segments further comprise a second outer electrode segment disposed forwardly of the first outer electrode segment, a third outer electrode segment disposed forwardly of the second outer electrode segment, and a fourth outer electrode segment disposed forwardly of the fourth outer electrode segment; and the at least two power supplies further comprise: a second power supply configured to apply a second voltage of the at least two voltages between the second inner electrode segment and the second outer electrode segment to generate an acceleration current configured to accelerate the source plasma along the acceleration region; a third power supply configured to apply a third voltage of the at least two voltages between the third inner electrode segment and the third outer electrode segment to generate a turning current configured to turn the source plasma inwardly toward the Z-pinch axis in the assembly region; and a fourth power supply configured to apply a fourth voltage of the at least two voltages between the fourth inner electrode segment and the fourth outer electrode segment to generate a Z-pinch current configured to flow along the Z-pinch plasma.

13. The plasma generation system of claim 12, wherein the second outer electrode segment extends entirely rearwardly of the front end of the inner electrode, wherein the third outer electrode segment extends partly forwardly of the front end of the inner electrode, and wherein the fourth outer electrode segment extends entirely forwardly of the front end of the inner electrode.

14. The plasma generation system of claim 12 or 13, wherein the first power supply is configured to start applying the first voltage before the second power supply is configured to start applying the second voltage, wherein the second power supply is configured to start applying the second voltage before the third power supply is configured to start applying the third voltage, and wherein the third power supply is configured to start applying the third voltage before the fourth power supply is configured to start applying the fourth voltage.

15. The plasma generation system of claim 1 or 2, further comprising a plasma formation and injection device comprising a plasma generator configured to generate the source plasma and inject the source plasma inside the acceleration region via a plasma injection port formed through the plasma confinement device.

16. The plasma generation system of claim 15, wherein the plasma generator comprises a plurality of plasma generators and the plasma injection port comprises a plurality of plasma injection ports, each plasma generator being configured to generate a respective portion of the source plasma and inject the respective portion of the source inside the acceleration region via a respective one a plurality of plasma injection ports.

17. The plasma generation system of claim 15 or 16, wherein the plasma generator comprises: an inner electrode; and an outer electrode surrounding the inner electrode to define a plasma formation region therebetween, the outer electrode extending beyond the inner electrode along a plasma formation axis to enclose a plasma transport channel extending from the plasma formation region to the plasma injection port along the plasma formation axis.

18. The plasma generation system of any one of claims 15 to 17, wherein the plasma formation and injection device comprises: a process gas supply unit configured to supply a process gas into the plasma formation region; and a plasma formation power supply configured to apply a voltage between the inner electrode and the outer electrode of the plasma generator to energize the process gas into the source plasma and cause the source plasma to flow along the plasma formation region and through the plasma transport channel to reach the plasma injection port for injection of the source plasma inside the acceleration region.

19. The plasma generation system of claim 18, wherein the process gas comprises deuterium, tritium, hydrogen, or helium, or any combination thereof.

20. The plasma generation system of any one of claims 15 to 19, wherein: the at least two inner electrode segments comprise a first inner electrode segment and a second inner electrode segment disposed forwardly of the first inner electrode segment; the at least two outer electrode segments comprise a first outer electrode segment and a second outer electrode segment disposed forwardly of the first outer electrode segment; and the at least two power supplies further comprise: a first power supply configured to apply a first voltage of the at least two voltages between the first inner electrode segment and the first outer electrode segment to generate an acceleration current configured to accelerate the source plasma along the acceleration region; and a second power supply configured to apply a second voltage of the at least two voltages between the second inner electrode segment and the second outer electrode segment to generate a turning current configured to turn the source plasma inwardly toward the Z-pinch axis in the assembly region and a Z-pinch current configured to flow along the Z-pinch plasma.

21. The plasma generation system of claim 20, wherein the second outer electrode segment extends partly forwardly of the front end of the inner electrode.

22. The plasma generation system of claim 20 or 21, wherein the first power supply is configured to start applying the first voltage before the second power supply is configured to start applying the second voltage.

23. The plasma generation of system any one of claims 15 to 19, wherein: the at least two inner electrode segments comprise a first inner electrode segment, a second inner electrode segment disposed forwardly of the first inner electrode segment, and a third inner electrode segment disposed forwardly of the second inner electrode segment; the at least two outer electrode segments comprise a first outer electrode segment, a second outer electrode segment disposed forwardly of the first outer electrode segment, and a third outer electrode segment disposed forwardly of the second outer electrode segment; and the at least two power supplies further comprise: a first power supply configured to apply a first voltage of the at least two voltages between the first inner electrode segment and the first outer electrode segment to generate an acceleration current configured to accelerate the source plasma along the acceleration region; a second power supply configured to apply a second voltage of the at least two voltages between the second inner electrode segment and the second outer electrode segment to generate a turning current configured to turn the source plasma inwardly toward the Z-pinch axis in the assembly region; and a third power supply configured to apply a third voltage of the at least two voltages between the third inner electrode segment and the third outer electrode segment to generate a Z-pinch current configured to flow along the Z-pinch plasma.

24. The plasma generation system of claim 23, wherein the second outer electrode segment extends partly forwardly of the front end of the inner electrode, and wherein the third outer electrode segment extends entirely forwardly of the front end of the inner electrode.

25. The plasma generation system of claim 23 or 24, wherein the first power supply is configured to start applying the first voltage before the second power supply is configured to start applying the second voltage, and wherein the second power supply is configured to start applying the second voltage before the third power supply is configured to start applying the third voltage.

26. The plasma generation system of any one of claims 1 to 25, wherein the Z-pinch plasma comprises a radially sheared axial flow.

27. The plasma generation system of any one of claims 1 to 26, wherein the inner electrode has a nose cone at the front end thereof, the nose cone forming at least part of the frontmost one of the at least two inner electrode segments.

28. The plasma generation system of any one of claims 1 to 27, wherein the number of the at least two inner electrode segments is the same as the number of the at least two outer electrode segments.

29. A plasma generation method comprising: providing a source plasma inside an acceleration region defined between an inner electrode and an outer electrode surrounding the inner electrode, wherein the inner electrode extends longitudinally between a front end and a rear end and comprises at least two inner electrode segments disposed successively along a Z-pinch axis, wherein the outer electrode extends longitudinally between a front end and a rear end and comprises at least two outer electrode segments disposed successively along the Z-pinch axis, and wherein the outer electrode extends forwardly beyond the inner electrode along the Z-pinch axis to define an assembly region adjacent the acceleration region and extending between the front end of the inner electrode and the front end of the outer electrode; and applying at least two voltages between the inner electrode and the outer electrode, each voltage being applied between one of the at least two inner electrode segments and one of the at least two outer electrode segments, wherein the application of the at least two voltages causes the source plasma to flow along the acceleration region and into the assembly region and to be compressed into a Z-pinch plasma along the Z-pinch axis in the assembly region.

30. The plasma generation method of claim 29, further comprising: providing at least one inner segment insulator longitudinally interleaved with the at least two inner electrode segments; and providing at least one outer segment insulator longitudinally interleaved with the at least two outer electrode segments.

31. The plasma generation method of claim 29 or 30, wherein: the at least two inner electrode segments comprise a first inner electrode segment; the at least two outer electrode segments comprise a first outer electrode segment; and providing the source plasma inside the acceleration region comprises: supplying a process gas inside the acceleration region; and applying a first voltage of the at least two voltages between the first inner electrode segment and the first outer electrode segment to generate an ionization current configured to ionize the process gas injected inside the acceleration region into the source plasma.

32. The plasma generation method claim 31, wherein: the at least two inner electrode segments further comprise a second inner electrode segment disposed forwardly of the first inner electrode segment, a third inner electrode segment disposed forwardly of the second inner electrode segment, and a fourth inner electrode segment disposed forwardly of the third inner electrode segment; the at least two outer electrode segments further comprise a second outer electrode segment disposed forwardly of the first outer electrode segment, a third outer electrode segment disposed forwardly of the second outer electrode segment, and a fourth outer electrode segment disposed forwardly of the fourth outer electrode segment; and applying the at least two voltages between the inner electrode and the outer electrode comprises: applying a second voltage of the at least two voltages between the second inner electrode segment and the second outer electrode segment to generate an acceleration current configured to accelerate the source plasma along the acceleration region; applying a third voltage of the at least two voltages between the third inner electrode segment and the third outer electrode segment to generate a turning current configured to turn the source plasma inwardly toward the Z-pinch axis in the assembly region; and applying a fourth voltage of the at least two voltages between the fourth inner electrode segment and the fourth outer electrode segment to generate a Z-pinch current configured to flow along the Z-pinch plasma.

33. The plasma generation method of claim 32, wherein the second outer electrode segment extends entirely rearwardly of the front end of the inner electrode, wherein the third outer electrode segment extends partly forwardly of the front end of the inner electrode, and wherein the fourth outer electrode segment extends entirely forwardly of the front end of the inner electrode.

34. The plasma generation method of claim 32 or 33, wherein the step of applying the first voltage is initiated before the step of applying the second voltage, wherein the step of applying the second voltage is initiated before the step of applying the third voltage, and wherein the step of applying the third voltage is initiated before the step of applying the fourth voltage.

35. The plasma generation method of claim 29 or 30, wherein providing the source plasma inside the acceleration region comprises: generating the source plasma outside the acceleration region; and injecting the source plasma inside the acceleration region.

36. The plasma generation method of claim 35, wherein: the at least two inner electrode segments comprise a first inner electrode segment, a second inner electrode segment disposed forwardly of the first inner electrode segment, and a third inner electrode segment disposed forwardly of the second inner electrode segment; the at least two outer electrode segments comprise a first outer electrode segment, a second outer electrode segment disposed forwardly of the first outer electrode segment, and a third outer electrode segment disposed forwardly of the second outer electrode segment; and applying the at least two voltages between the inner electrode and the outer electrode further comprises: applying a first voltage of the at least two voltages between the first inner electrode segment and the first outer electrode segment to generate an acceleration current configured to accelerate the source plasma along the acceleration region; applying a second voltage of the at least two voltages between the second inner electrode segment and the second outer electrode segment to generate a turning current configured to turn the source plasma inwardly toward the Z-pinch axis in the assembly region; and applying a third voltage of the at least two voltages between the third inner electrode segment and the third outer electrode segment to generate a Z-pinch current configured to flow along the Z-pinch plasma.

37. The plasma generation method of claim 36, wherein the second outer electrode segment extends partly forwardly of the front end of the inner electrode, and wherein the third outer electrode segment extends entirely forwardly of the front end of the inner electrode.

38. The plasma generation method of claim 36 or 37, wherein the step of applying the first voltage is initiated before the step of applying the second voltage, and wherein the step of applying the second voltage is initiated before the step of applying the third voltage.