CN104134516A - Secondary inner cylinder having high voltage superposition efficiency - Google Patents

Abstract

The invention provides a secondary inner cylinder having high voltage superposition efficiency. A smooth transition structure is shown on the surface of an impedance conversion segment of the secondary inner cylinder, the running impedance of the impedance conversion segment of a magnetic insulation transmission line formed by the secondary inner cylinder and the inner wall of an induction cavity unit is in the form of exponential conversion, the average impedance of the magnetic insulation transmission line is obviously smaller than that of a conical or a stepped secondary inner cylinder, thereby being favorable for reducing reflected waves at a feeding port of each induction cavity unit and improving voltage coupling efficiency. Meanwhile, the research results show that the standard exponential impedance conversion form has highest power transmission efficiency, so that high pulse voltage peak can be obtained at the load, and when overmatching coefficient p is larger than 1.5, the voltage superposition efficiency of the secondary inner cylinder is superior to that of the conical or stepped secondary inner cylinder.

Description

A kind of secondary inner core with high voltage stack efficiency

Technical field

The present invention relates to a kind of can efficient coupling, the secondary inner core of stack and through-put power pulse, be applied to have converging and transmitting of (as drive sources such as magnetic insulation induced voltage superimposer, linear type transformer driving sources) pulse power in the large-scale pulse power device of plural serial stage feature.

Background technology

Magnetic insulation induced voltage superimposer (MIVAs) has been widely used in the high power particle beams (electron beam, ion beam) generation and radiation environment simulation (x ray, gamma-rays).Generally, different number induction cavity modules drive the output pulses parameter of demand to produce dissimilar load by magnetic insulation transmission line (MITL) series connection, as devices such as No. one, Hermes-III, RITS, Sygnus, sword light.And MITL electrical length is generally greater than through-put power burst length width or suitable with it, its impedance transformation form along the line has appreciable impact to multistage induction cavity superimposed pulses efficiency, and therefore exploring best MITL impedance (operation impedance) variation has higher academic significance and engineering using value.

In engineering reality, the MITL of induced voltage superimposer is comprised of level inner core and series inductance cavity wall, because induction cavity inwall size is subject to the restriction of unit module, under the definite condition of induction cavity, its physical dimension is solidified thereupon, therefore, MITL impedance transformation can only be realized by adjusting its secondary inner tube structure.At present, two kinds of secondary inner tube structures are proposed in the world, i.e. pyramidal structure and ladder-type structure.Pyramidal structure is that secondary inner diameter of steel flue is linearity from first order induction cavity top to afterbody induction cavity top and reduces process, as shown in Figure 1, secondary inner core changeover portion integral body is a cone-shaped structure, for example: at J.J.Ramirez, D.E.Hasti, the scholars' such as J.P.Corley < < The four stage HELIA experiment > > (6 ^thiEEE International Pulsed Power Conference, Arlington, Virginia, 1987, pp.146-143.) in, introduced a level Four induction cavity series impedance and by 8 Ω, be converted into the MITL of 28 Ω, secondary inner core has adopted typical pyramidal structure first.This design feature is that inner core surface transition is comparatively smooth, is conducive to the uniform emission of field-causing electron under magnetic insulation state, thereby reduces vacuum electric subflow share along the line; But for each induction cavity, it has higher average impedance than stairstepping inner core, and the induction cavity feed voltage wave distortion problem that exists non-homogeneous impedance to cause, so voltage stack efficiency is lower.Ladder-type structure is that secondary inner diameter of steel flue is from first order induction cavity end to stepped the reducing in afterbody induction cavity top, as shown in Figure 2, and the secondary inner diameter of steel flue of every grade of corresponding length of induction cavity remains unchanged, between each induction cavity adjacent cells, MITL impedance transformation value is identical, for example, at V.L.Bailly, D.L.Johnson, the scholars' such as P.Corcoran < < Design of a high impedance MITL for RITS-3 > > (14 ^thiEEE International Pulsed Power Conference, Dallas, Texas, 2003, pp.399-402.) in, introduce two three grades of induction cavity series impedances and by 8 Ω, be converted into the MITL that 24 Ω and 14.3 Ω are converted into 42.9 Ω respectively, its secondary inner core all adopts step structure, and every MITL impedance transformations at different levels are respectively 8 Ω and 14.3 Ω.This design feature is that each induction cavity is to MITL system feed voltage, electric current (that is, power stream is identical) in full accord, and can keep preferably PFL feed-in waveform, therefore has higher voltage stack efficiency; But due to the existence of its ladder transition structure, there is local crowning more or less in tapering transition relatively, makes it in magnetic insulation operating state end, cause emission space electronics relatively many, and then increased vacuum electric subflow ratio, reduced the effective operating current of load.

Summary of the invention

For overcoming the secondary inner core of existing taper and stairstepping, there is respectively the voltage stack efficiency deficiency with introducing a large amount of vacuum electric subflows aspect on the low side, the operation impedance that the invention provides a kind of magnetic insulation transmission line impedance transforming section is the secondary inner tube structure of designation number conversion, this structure can effectively avoided under the condition of a large amount of Field Electron Emissions, further improve the voltage stack efficiency of MIVAs, have the main advantage of taper and stairstepping secondary structure concurrently.

Technical solution of the present invention:

A secondary inner core with high voltage stack efficiency, its special character is:

The impedance transformation section surface of described secondary inner core 4 presents smooth transition structure, and the operation impedance of the transformer section of the magnetic insulation transmission line that forms of secondary inner core and induction cavity unit inwall is descriptor index fractal transform form, shown in (1):

$\left\{\begin{array}{c}Z\left(x\right)=A+B\&CenterDot;\exp (a\&CenterDot;x)\\ a=n\&CenterDot;\ln (Z_{\mathrm{out}}/Z_{\mathrm{in}})\&CenterDot;L^{-1}\\ B=(Z_{\mathrm{out}}-Z_{\mathrm{in}})\&CenterDot;{[{\left(\frac{Z_{\mathrm{out}}}{Z_{\mathrm{in}}}\right)}^n-1]}^{-1}\\ A=Z_{\mathrm{in}}-(Z_{\mathrm{out}}-Z_{\mathrm{in}})\&CenterDot;{[{\left(\frac{Z_{\mathrm{out}}}{Z_{\mathrm{in}}}\right)}^n-1]}^{-1}\\ Z_{\mathrm{out}}=p\&CenterDot;N\&CenterDot;Z_{\mathrm{cav}}\\ Z_{\mathrm{in}}=p\&CenterDot;Z_{\mathrm{cav}}\end{array}\right.---\left(1\right)$

L: the transformer section of magnetic insulation transmission line geometrical length vertically, unit: m;

X: along the distance between the transformer section top of secondary inner core axial distance magnetic insulation transmission line, 0≤x≤L, unit: m;

Zcav: single induction cavity unit equiva lent impedance, unit: Ω;

P: magnetic insulation transmission line is with respect to the overmatching coefficient of induction cavity equiva lent impedance, p >=1, dimensionless;

N: induction cavity series connection number, nondimensional;

A, B are constant factor, dimensionless;

α: descriptor index coefficient, unit: m ^-1;

N: designation number coefficient, the arbitrary real constant except zero, dimensionless;

Z _out: the impedance of magnetic insulation induced voltage superimposer secondary output end, unit: Ω;

Z _in: the secondary sending-end impedance of magnetic insulation induced voltage superimposer, unit: Ω.

When the n in formula (1) equals 1, the operation impedance of the transformer section of the magnetic insulation transmission line that secondary inner core and induction cavity unit inwall form is designation number fractal transform form, meets formula (2):

$Z\left(x\right)=p\&CenterDot;Z_{\mathrm{cav}}\&CenterDot;\exp (\frac{x}{L}\&CenterDot;\ln \left(N\right))---\left(2\right).$

When not considering the affecting of operation impedance of the magnetic insulation transmission line that space electronic forms secondary inner core and induction cavity unit inwall, secondary inner diameter of steel flue a (x) meets following formula (3),

$a\left(x\right)=\frac{b}{\exp (Z\left(x\right)/60)}---\left(3\right)$

B: induction cavity unit inner diameter, unit: m.

When considering space electronic to the operation impedance influences of magnetic insulation transmission line, secondary inner core position diameter needs, according to concrete electric and structural parameters, in conjunction with PIC simulation analysis result, to determine.

When induced voltage superimposer is formed by H level induction cavity units in series, the operation impedance of the magnetic insulation transmission line section corresponding with first order induction cavity unit be about single induction cavity unit equiva lent impedance p doubly; From first order induction cavity cell end, start to finish to top, afterbody induction cavity unit, the operation impedance of the magnetic insulation transmission line section of corresponding part is transformed to H * p induction cavity unit equiva lent impedance doubly by p induction cavity unit equiva lent impedance doubly, and is designation number shape impedance transformation form; The impedance of the operation impedance of the magnetic insulation transmission line section that afterbody induction cavity unit is corresponding and the extension of magnetic insulation transmission line is consistent.

Advantage of the present invention:

1, secondary inner core of the present invention surface presents smooth transition completely, along face, does not have local projection, and a uniform space electron emission is more even, is conducive to reduce the vacuum electric subflow share under magnetic insulation state.

2, the average operation impedance average impedance of the transformer section of magnetic insulation transmission line of the present invention is significantly less than taper and stairstepping, is conducive to reduce the reflected wave of each induction cavity unit feed-in port, improves voltage coupling efficiency; Simultaneously, show after deliberation, designation number shape impedance transformation form has the highest power transmission efficiency, therefore can in load, obtain higher crest value of impulse voltage, overmatching coefficient p is greater than at 1.5 o'clock, is better than the voltage stack efficiency of stairstepping and the secondary inner core of taper.

Accompanying drawing explanation

Fig. 1 is the secondary inner tube structure schematic diagram of taper; Wherein

Fig. 2 is the secondary inner tube structure schematic diagram of stairstepping;

Fig. 3 is the secondary inner tube structure schematic diagram of designation number shape;

Fig. 4 is ten grades of induction cavity cascaded structure schematic diagrames;

Fig. 5 is the secondary inner diameter of steel flue change curve of taper and designation number shape, and wherein solid line is the secondary inner diameter of steel flue change curve of designation number shape, and dotted line is the secondary inner diameter of steel flue change curve of taper;

Fig. 6 is that three kinds of typical impedance variations are with the change curve of transmission line element number;

Fig. 7 be under three kinds of typical impedance variations load voltage peak value with the change curve of damping coefficient;

In figure, 1-forms line (PFL) feed-in pulse; 2-induction cavity unit; 3-induction cavity inwall; 4-level inner core; 5-magnetic insulation transmission line (MITL); 6-MITL extension; 7-load, the expression symbol of-symmetry axis.

Embodiment

In the present invention, the operation impedance of the transformer section of the magnetic insulation transmission line that secondary inner core 4 and induction cavity unit inwall form can adopt a kind of definition of descriptor index variation, that is:

$\left\{\begin{array}{c}Z\left(x\right)=A+B\&CenterDot;\exp (a\&CenterDot;x)\\ a=n\&CenterDot;\ln (Z_{\mathrm{out}}/Z_{\mathrm{in}})\&CenterDot;L^{-1}\\ B=(Z_{\mathrm{out}}-Z_{\mathrm{in}})\&CenterDot;{[{\left(\frac{Z_{\mathrm{out}}}{Z_{\mathrm{in}}}\right)}^n-1]}^{-1}\\ A=Z_{\mathrm{in}}-(Z_{\mathrm{out}}-Z_{\mathrm{in}})\&CenterDot;{[{\left(\frac{Z_{\mathrm{out}}}{Z_{\mathrm{in}}}\right)}^n-1]}^{-1}\\ Z_{\mathrm{out}}=p\&CenterDot;N\&CenterDot;Z_{\mathrm{cav}}\\ Z_{\mathrm{in}}=p\&CenterDot;Z_{\mathrm{cav}}\end{array}\right.---\left(1\right)$

Wherein, A, B are constant factor, dimensionless; α is descriptor index coefficient, unit: m ^-1; N is designation number coefficient, the arbitrary real constant except zero, dimensionless; Z _outfor the impedance of MIVAs secondary output end, unit: Ω; Z _infor the sending-end impedance of MIVAs level, unit: Ω; L is magnetic insulation transmission line impedance transforming section geometrical length vertically, unit: m; X is along the distance (0≤x≤L) between secondary inner core axial distance magnetic insulation transmission line impedance transforming section top, unit: m; Z _cavfor single induction cavity unit (cavity) equiva lent impedance, unit: Ω; P is that magnetic insulation transmission line is with respect to the overmatching coefficient (p>=1) of induction cavity cell impedance, dimensionless; N is induction cavity series connection number, nondimensional.

It is to be noted, when n=1, the operation impedance design of the transformer section of the magnetic insulation transmission line that the secondary inner core 4 of induced voltage superimposer and induction cavity unit inwall form is for being designation number fractal transform form, formula (1) can be reduced to formula (2), now can obtain the highest voltage stack efficiency, otherwise voltage stack efficiency can decrease, but stand good under the less demanding condition of voltage stack efficiency.

$Z\left(x\right)=p\&CenterDot;Z_{\mathrm{cav}}\&CenterDot;\exp (\frac{x}{L}\&CenterDot;\ln \left(N\right))---\left(2\right)$

When not considering that space electronic moves affecting of impedance to magnetic insulation transmission line, its secondary inner diameter of steel flue a (x) can further be expressed as (as shown in Equation 4),

$a\left(x\right)=\frac{b}{\exp \left(\frac{p\&CenterDot;Z_{\mathrm{cav}}\&CenterDot;\exp (\frac{x}{L}\&CenterDot;\ln \left(N\right))}{60}\right)}---\left(4\right)$

Wherein, b is induction cavity inner diameter, unit: m.

When considering space electronic to magnetic insulation transmission line operation impedance influences, need be for concrete induced voltage superimposer electric parameter and geometric parameter, utilize particle simulation (PIC) instrument, structure meets the secondary inner tube structure of formula (2) impedance transformation form, makes its operation impedance be designation number fractal transform form.

Below for an example, also by reference to the accompanying drawings this embodiment is elaborated.

In the present embodiment, whole induced voltage superimposer is in series by ten grades of induction cavity unit 2, and each induction cavity unit 2 is identical, as shown in Figure 4.Induction cavity unit equiva lent impedance approximately 6 Ω, along the about 4.5ns of axis electrical length, induction cavity inwall 3 diameter 0.4m; Every grade of induction cavity unit 2 forms line feed-in pulse 1 by one and drives, and forms the line about 1MV of potential pulse peak value that moves ahead.The magnetic insulation transmission line 5 with designation number shape impedance transformation form of the present invention is arranged and is formed by the secondary inner core 4 of this induced voltage superimposer and induction cavity inwall 3 coaxial lines; 5 sections of impedances of magnetic insulation transmission line of first order induction cavity unit 2 correspondences are about p times of (p is overmatching coefficient, with definition above), i.e. 6p Ω of its equiva lent impedance; The 5 sections of operation impedances of magnetic insulation transmission line that start to finish to 2 tops, afterbody induction cavity unit corresponding part from first order induction cavity unit 2 ends are transformed to 60p Ω by 6p Ω, and be designation number shape impedance transformation form, suc as formula (2) mathematic(al) representation, define; 5 sections of impedances of magnetic insulation transmission line and 6 impedances of magnetic insulation transmission line extension that afterbody induction cavity is corresponding are consistent, and are about 60p Ω.

When not considering magnetic insulation transmission line 5 vacuum electric sublayers on operation the affecting of impedance, secondary inner core 4 diameters are by the definition of formula (3) mathematic(al) representation, as solid line in Fig. 5 changes.While considering space electronic to magnetic insulation transmission line 5 operation impedance influences, secondary inner core 4 position diameters need, according to concrete electric and structural parameters, in conjunction with PIC simulation analysis result, to determine.

Secondary inner core 4 impedance transformation section surfaces are similar with pyramidal structure, present smooth transition structure completely, can effectively avoid the existence of a large amount of field emission space electronics that local crowning causes.

Magnetic insulation transmission line 5 average impedances of designation number fractal transform are less than the average impedance of taper and stairstepping conversion, as shown in Figure 6, can effectively reduce the voltage reflection of 2 feed-in magnetic insulation transmission line 5 ports, induction cavity unit; It has higher voltage transmission efficiency simultaneously, therefore can in load 7, obtain higher voltage magnitude, as shown in Figure 7.

Secondary inner core 4 concrete structure parameters in the present invention are not unique, can adjust with structural parameters and load 7 parameters according to induction cavity unit 2 is electric, but anyway adjust all to need to meet, make its corresponding section magnetic insulation transmission line 5 operation impedance transformations be designation number shape feature; If when less demanding to voltage stack efficiency, also can make secondary magnetic insulation transmission line operation transformer section be the feature of descriptor index variation.

Claims (5)

1. a secondary inner core with high voltage stack efficiency, is characterized in that:

The impedance transformation section surface of described secondary inner core presents smooth transition structure, and the operation impedance of the transformer section of the magnetic insulation transmission line that forms of secondary inner core and induction cavity unit inwall is descriptor index fractal transform form, shown in (1):

$\left\{\begin{array}{c}Z\left(x\right)=A+B\&CenterDot;\exp (a\&CenterDot;x)\\ a=n\&CenterDot;\ln (Z_{\mathrm{out}}/Z_{\mathrm{in}})\&CenterDot;L^{-1}\\ B=(Z_{\mathrm{out}}-Z_{\mathrm{in}})\&CenterDot;{[{\left(\frac{Z_{\mathrm{out}}}{Z_{\mathrm{in}}}\right)}^n-1]}^{-1}\\ A=Z_{\mathrm{in}}-(Z_{\mathrm{out}}-Z_{\mathrm{in}})\&CenterDot;{[{\left(\frac{Z_{\mathrm{out}}}{Z_{\mathrm{in}}}\right)}^n-1]}^{-1}\\ Z_{\mathrm{out}}=p\&CenterDot;N\&CenterDot;Z_{\mathrm{cav}}\\ Z_{\mathrm{in}}=p\&CenterDot;Z_{\mathrm{cav}}\end{array}\right.---\left(1\right)$

L: the transformer section of magnetic insulation transmission line geometrical length vertically, unit: m;

X: along the distance between the transformer section top of secondary inner core axial distance magnetic insulation transmission line, 0≤x≤L, unit: m;

Zcav: single induction cavity unit equiva lent impedance, unit: Ω;

P: magnetic insulation transmission line is with respect to the overmatching coefficient of induction cavity equiva lent impedance, p >=1, dimensionless;

N: induction cavity series connection number, nondimensional;

A, B are constant factor, dimensionless;

α: descriptor index coefficient, unit: m ^-1;

N: designation number coefficient, the arbitrary real constant except zero, dimensionless;

Z _out: the impedance of magnetic insulation induced voltage superimposer secondary output end, unit: Ω;

Z _in: the secondary sending-end impedance of magnetic insulation induced voltage superimposer, unit: Ω.

2. the secondary inner core with high voltage stack efficiency according to claim 1, it is characterized in that: when the n in formula (1) equals 1, the operation impedance of the transformer section of the magnetic insulation transmission line that secondary inner core and induction cavity unit inwall form is designation number fractal transform form, meets formula (2):

$Z\left(x\right)=p\&CenterDot;Z_{\mathrm{cav}}\&CenterDot;\exp (\frac{x}{L}\&CenterDot;\ln \left(N\right))---\left(2\right).$

3. the secondary inner core with high voltage stack efficiency according to claim 1 and 2, is characterized in that:

When not considering the affecting of operation impedance of the magnetic insulation transmission line that space electronic forms secondary inner core and induction cavity unit inwall, secondary inner diameter of steel flue a (x) meets following formula (3),

$a\left(x\right)=\frac{b}{\exp (Z\left(x\right)/60)}---\left(3\right)$

B: induction cavity unit inner diameter, unit: m.

4. the secondary inner core with high voltage stack efficiency according to claim 1, is characterized in that:

When considering space electronic to the operation impedance influences of magnetic insulation transmission line, secondary inner core position diameter needs, according to concrete electric and structural parameters, in conjunction with PIC simulation analysis result, to determine.

5. the secondary inner core with high voltage stack efficiency according to claim 1 and 2, is characterized in that:

When induced voltage superimposer is formed by H level induction cavity units in series, the operation impedance of the magnetic insulation transmission line section corresponding with first order induction cavity unit be about single induction cavity unit equiva lent impedance p doubly; From first order induction cavity cell end, start to finish to top, afterbody induction cavity unit, the operation impedance of the magnetic insulation transmission line section of corresponding part is transformed to H * p induction cavity unit equiva lent impedance doubly by p induction cavity unit equiva lent impedance doubly, and is designation number shape impedance transformation form; The impedance of the operation impedance of the magnetic insulation transmission line section that afterbody induction cavity unit is corresponding and the extension of magnetic insulation transmission line is consistent.