CN101777730B - Designing method of graphite electrode of high energy pulse gas switch - Google Patents
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Abstract
The invention discloses a designing method of a graphite electrode of a high energy pulse gas switch. In the method, key parameters of the electrode of the gas switch can be determined according to designing steps provided by the invention as long as single transfer charge quantity, working voltage, working room temperature, reliable conducting frequencies and the density and the ablativity of graphite material selected by the graphite electrode in engineering design requirements of a pulse energy storage discharge device are known. By using the designing method, a corresponding two-electrode graphite type gas switch can be designed and manufactured with scientific grounds by aiming at different high-power high-energy pulse discharge devices, and the designing method can also be used for calculating and inspecting whether a certain type of graphite electrode gas switch is suitable for working in a certain specific pulse energy storage discharge device or not, thereby avoiding the blindness in the process of researching and manufacturing the gas switch, also avoiding traditional engineering methods of testing for a long time by establishing test platforms with the same parameters and saving a great deal of labor power, financial resources and material resources.
Description
Technical Field
The invention belongs to the technical field of high-voltage electrical appliances and pulse power, and relates to a design method of a graphite electrode of a high-energy pulse gas switch.
Background
Pulse power technology refers to an electro-physical technology that stores energy with a high density for a long time, compresses and converts the energy rapidly or releases the energy directly to a load in a short time. Switching devices take a particular position in pulsed power systems because the parameters and characteristics of the switching devices have the most direct and sensitive impact on the rise time, amplitude, etc. of the pulses. For a pulse power device, its performance is not at all excessive, determined by the characteristics of the switches used. Any advance in the ability to deliver stored energy to a load is premised on the successful design and development of a wide variety of pulsed high current switches.
In the application occasions of pulse power technologies such as a strong laser device, a strong magnetic field device, high-power microwave, high-energy plasma and the like, the requirements on the switch mainly include high voltage and strong current resistance, short breakdown time delay, small dispersity, small inductance and resistance, less electrode ablation, large transferred charge amount of single trigger conduction and high reliability. For example, a two-electrode gas switch used in a nif (national Ignition facility) device in the united states needs to operate in a 2.0MJ primary energy module, can withstand a 24kV dc voltage without self-breakdown, can pass a large current of 500kA, has a transfer charge amount of 150Cb (coulomb) for single-trigger conduction, has an electrode ablation rate of 100 μ g/Cb (microgram per coulomb), has a reliable conduction frequency of more than 1500 times, does not need maintenance and replacement, and is low in price.
The gas switch has the advantages of fast response, low loss, high voltage bearing capacity, large conduction current, high stability, low inductance, convenient working voltage regulation, simple and firm structure, low manufacturing cost and the like, thereby being more suitable for being applied to the technical field of high-energy pulse power. Common gas spark switches include three-electrode field-distortion spark switches, two-electrode gas spark switches, and the like. The gas switch in the high-voltage and high-current field can generate strong electric arcs in gas gaps, and the temperature of the electric arcs can reach thousands of even tens of thousands of degrees centigrade along with the change of parameters such as gas pressure in the switch, the strength of electric field, the size of passing current and the like. High-energy pulse switches generally cannot adopt a three-electrode structure with a trigger electrode, because the trigger electrode is very seriously ablated when high current is passed through, frequent maintenance is needed, and the reliable service life of the switch is very short.
In the past, the traditional metal materials such as copper and copper-tungsten alloy are largely used in China to manufacture the electrode of the high-energy pulse switch. Graphite has become an increasingly popular electrode material in current applications. The advantages of graphite over copper and other metal materials are mainly the following:
(1) the machining speed of the graphite is high. Typically, processing graphite materials using numerically controlled equipment can be 2 to 5 times faster than processing the same copper material.
(2) The graphite is light in weight, has a density of 1.7-1.9 grams per cubic centimeter and is only 1/5 parts of copper.
(3) Graphite only has gas phase and solid phase, the sublimation temperature is 3650 ℃, and the thermal expansion coefficient is only 1/30 of copper; the softening point of copper is about 1000 ℃, and the copper is easy to deform due to heating; the copper and copper-tungsten alloy materials are easy to generate electrode ablation splashing due to the existence of liquid phase, and pits or bulges can be formed on the surface of the electrode after liquefaction and cooling, so that the field intensity uniformity of the surface of the electrode is damaged.
Therefore, the gas switch adopting the pure graphite electrode is a novel device applied to the technical field of high-energy pulse power, and the content related to the invention is the electrode design method of the switch.
Disclosure of Invention
The invention aims to provide a graphite electrode design method of a high-energy pulse gas switch aiming at engineering application occasions requiring pulse power technology, such as a strong laser device, a strong magnetic field device, high-power microwaves, high-energy plasmas and the like.
The invention provides a design method of a graphite electrode of a high-energy pulse gas switch, which is characterized by comprising the following steps:
selecting a graphite material with the average grain diameter of less than or equal to 3 and the Shore hardness of more than or equal to 70 in the step 2, and acquiring two parameters of the density rho and the electrode ablation rate deltam of the graphite material, wherein the unit of the density rho is g/cm3The unit of the electrode ablation rate delta m is g/Cb;
step 4, calculating the gas gap distance d in the expected service life N by using a formula I, and calculating the effective height H of the graphite electrode in the expected service life N by using a formula II; calculating the self-breakdown voltage U maintained inside the gas switch within the expected service life N using equation IIIbThe internal inflation pressure P to be set is substantially constant,
d＝d0+2 × Δ h formula I
Wherein, <math>
<mrow>
<mi>Δh</mi>
<mo>=</mo>
<mfrac>
<mrow>
<mi>N</mi>
<mo>×</mo>
<mi>δm</mi>
<mo>×</mo>
<mi>Q</mi>
</mrow>
<mrow>
<mi>π</mi>
<msup>
<mi>R</mi>
<mn>2</mn>
</msup>
<mo>×</mo>
<mi>ρ</mi>
</mrow>
</mfrac>
</mrow>
</math>
H＝h0- Δ h formula II
Wherein A is0And B0Is a constant;
step 5, judging whether the following three conditions are all met, if so, turning to step 7, otherwise, turning to step 6;
condition 1: (d-d)0)/d0Less than or equal to 50 percent;
condition 2: h is more than 0;
condition 3: p is greater than 1 standard atmosphere;
step 6, processing the conditions which are not satisfied in the step 5 according to the following requirements, and then switching to step 4: condition 1 is not satisfied, R is increased, or d is increased0(ii) a Condition 2 is not satisfied, and the initial effective height h of the electrode is increased0(ii) a If the condition 3 is not met, increasing the radius R of the graphite electrode;
and 7, designing the graphite electrode by using the obtained parameters d, H and R of the graphite electrode.
The invention provides that the key parameters of the gas switch electrode can be determined according to the design steps given by the invention as long as the single transfer charge quantity, the working voltage, the working room temperature and the reliable conduction times of the switch conduction in the engineering design requirements of the pulse energy storage discharge device are known, and the density and the ablation rate of the graphite material selected by the graphite electrode.
The design method provided by the invention can be used for designing and manufacturing corresponding two-electrode graphite type gas switches aiming at different high-power high-energy pulse discharge devices with scientific basis, and can also be used for calculating and checking whether a certain graphite electrode gas switch is suitable for working in a certain specific pulse energy storage discharge device, thereby avoiding the blindness in the process of developing the gas switch, avoiding the traditional engineering method for establishing a test platform with the same parameters for long-time test, and saving a large amount of manpower, financial resources and material resources.
Drawings
FIG. 1 is a cross-sectional view of a gas switch graphite electrode in accordance with the present invention; in the figure, 1 is a graphite electrode, 2 is an electrode mounting clamp, 3 is an electrode holder, d is a gas gap distance, H is an electrode effective height, R is a graphite electrode radius, and d, H and R are key parameters to be solved in electrode design.
Detailed Description
The invention will be further described with reference to the following figures.
The invention provides that the following two points need to be noticed when the graphite material is used for manufacturing the high-energy pulse gas switch electrode:
(1) selecting high-density high-hardness isotropic ultrafine particle graphite material. For graphite for electrodes to pass peak current of several hundred kA, the average particle diameter should not be higher than 3 and shore hardness should not be lower than 70.
(2) Graphite is more brittle than copper, so the design of the graphite electrode shape should avoid sharp-angle edges as much as possible, otherwise graphite collapse is easily caused under the action of large impact electromotive force caused by large current. For the inevitably sharp edges, the fastening of the electrode should be strengthened and shock absorbing measures should be taken into consideration.
The invention provides that the opposite surfaces of the upper graphite and the lower graphite of the high-energy pulse switch meet the design of an isoelectric field surface so as to ensure that the electric field intensity of an air gap formed by the upper graphite electrode and the lower graphite electrode is equal everywhere after direct current high voltage is applied to the air gap. This is because the two-electrode gas switch generally operates in a commanded-trigger conduction mode. The trigger command is generated by a high-voltage pulse device, such as a pulse transformer, a Marx generator, an ignition coil and the like, and a pulse wave with short rise time and high peak voltage is generated. The upper and lower graphite electrodes of the two-electrode gas switch jointly form a gas gap. After the direct current high voltage is applied externally, the gas gap can be equivalent to a parallel plate uniform electric field, and the electric field intensity is equal everywhere. Thus, when a trigger pulse generated by a trigger command is applied to the gas switch gap, the gap trigger breaks down as long as a valid electron is present somewhere in the gas gap. The position of the discharge point is changed along with the position of the effective electron appearance point and is randomly and uniformly distributed on the whole electrode surface, and the electrode life and the trigger characteristic of the surface shape are the best. Otherwise, the arc starting point of the arc when the switch is conducted is concentrated on some places on the surface of the electrode, and after the switch is conducted for many times, the part of the electrode is seriously ablated, which is not beneficial to prolonging the service life of the electrode. Specific implementations may use Rogowski (Rogowski) or Bruse (brush) electrodes, as well as rounded electrodes, as may processing conditions and accuracy limitations.
On the basis of the design of an electric field surface such as a graphite electrode, the electrode design method provided by the invention is also based on the following two facts proved by tests: (fact 1) the graphite ablation process is mainly a solid-to-gas phase transformation, i.e. sublimation; (fact 2) the mass loss at the ablation site of graphite electrodes (i.e., ablation rate) increases and decreases linearly with the amount of transferred charge only when a high transferred-charge discharge with a transferred-charge amount greater than 25Cb is applied.
The invention provides that the key parameters required to be determined for designing the graphite electrode of the gas switch comprise the radius R (or the diameter) of the electrode, the distance d of a gas gap (or the distance between the end faces of the electrode), the effective height H of the electrode and the setting of the inflation pressure in the switch.
The invention also provides that, in order to determine the above-mentioned key parameters, the single transfer charge amount, the working voltage, the working room temperature and the reliable conduction times of the switch conduction in the engineering design requirement of the known pulse energy storage discharge device, and the density and the ablation rate of the graphite material selected by the graphite electrode, the key parameters of the graphite electrode of the gas switch shown in fig. 1 can be calculated and determined step by step according to the design theory to be derived next: gas gap distance d, electrode effective height H, graphite electrode radius R.
The following is a theoretical explanation of the design of the present invention.
In general, ablation of an electrode is the result of concentrated release of energy from the surface and subsurface layers of the electrode, causing melting and vaporization of the electrode material, and in theory, the ablated volume of electrode material can be divided into two portions, given by:
ve＝kmvm+kvvv(formula 1)
Wherein v ismIs the melting volume of the electrode, vvIs the evaporation volume of the electrode, kmAnd kvRespectively as a result of melting and vaporisationAnd (4) adding the active ingredients. When k ism1 and kvWhen the melting point is 0, the electrode material is completely ablated in a liquefying mode; when k ism0 and kvThe extreme case of complete ablation of the electrode material by vaporization (pure vapor phase erosion) is 1. (equation 1) is equally suitable for correlation analysis of ablation quality.
Since the gas gap formed by the upper and lower graphite electrodes is an isoelectric surface with equal electric field intensity everywhere, the effective area of the electrodes for generating discharge is considered to be a circle with an equivalent radius R, and the area of the area where the electrodes can be ablated after discharge is considered to be
S＝πR2(formula 2)
Due to (fact 2), the mass loss of the ablation point of the graphite electrode is linearly increased and decreased with the transfer charge amount, and assuming that the transfer charge amount passing through each conducting time of the gas switch is Q (unit: Cb), and the ablation rate of the graphite electrode caused by each coulomb transfer charge is δ m (unit: g/Cb), the mass Δ m lost by the graphite electrode per using time can be expressed as:
Δ m ═ δ m × Q (Q > 25Cb) (equation 3)
The density of the graphite material is expressed as p, which is generally 1.7g/cm3～1.9g/cm3The graphite materials with different labels have slightly different densities. Since (fact 1) graphite ablation is mainly a solid-to-gas phase transformation, in combination with (equation 1), there are
Where Δ v is the ablated volume of the graphite electrode after each on-discharge.
For a graphite electrode designed to have an isoelectric field surface, the positions of the discharge points are uniformly distributed on the whole electrode surface, and after conducting for a plurality of times (assuming conducting discharge times N), the ablation points are also uniformly distributed on the whole electrode surface, so that the mass loss of ablation on all parts of the electrode surface is also uniform, the height change of the electrode surface caused by ablation is also uniform, and the height change is expressed by Δ h, and the following equation is satisfied:
sxΔ h ═ nxΔ v (formula 5)
Substituting (equation 4) into (equation 5) yields:
Further, substituting (equation 2) into (equation 6) can yield:
It is clear that an increase in Δ h means that the gas gap distance of the two-electrode switch will varyLarge, assuming an initial state, the design gas gap distance of a brand new graphite type gas switch is d0The effective height of the graphite electrode is represented by H, and the initial value is H0After using this switch N times, the gas gap distance will become:
d＝d0+2 × Δ h (formula 8)
And the effective height of the graphite electrode will become
H＝h0Δ h (equation 9)
The larger the gas gap distance, the more the static characteristic of the dc withstand voltage of the switch will change significantly, and the static characteristic of the dc withstand voltage under the working condition of the gas switch is the designed value set in advance. Therefore, the internal inflation pressure of the gas switch must be adjusted accordingly to maintain the dc withstand voltage static characteristics of the gas switch under operating conditions. Let UbThe self-breakdown voltage reflecting the static characteristic of the gas gap DC voltage resistance, d the gas gap distance and chi the relative density of the gas, the invention uses the following quantitative calculation formula to reflect UbAnd d χ:
Wherein A is0And B0Is a constant number, UbIn kV, and d in cm. The interior of the graphite electrode gas switch is filled with dry air, and chi can be expressed as:
Where P is gas pressure (kPa) and t is temperature in degrees Celsius. Substituting (equation 7), (equation 8), and (equation 11) into (equation 10) can yield:
(formula 12)
(equation 12) can be abbreviated as:
F(d0，δm，R，ρ，Q，N，P，t，Ub) Not equal to 0 (formula 13)
(equation 13) shows that, at the parameter d0，δm，R，ρ，Q，N，P，t，UbIn the method, any one parameter is unknown, and the unknown parameter can be calculated according to the rest known parameters. The theoretical derivation of the present invention is thus completed.
When the d chi value of the gas switch is not very large (not more than 10)5Pa × cm magnitude), (formula 12) can be a0＝24.5，B0＝6.4。
From the above analysis, the design steps of the high-energy pulse gas switch pure graphite electrode related to the invention can be given as follows:
step (1) determining the expected service life N (times) and the self-breakdown voltage U according to the engineering technical requirementsbThe working temperature t (DEG C) and the single transfer charge quantity Q;
selecting a graphite material (the average particle size of the graphite material is required to be less than or equal to 3, and the Shore hardness is required to be greater than or equal to 70), and obtaining two parameters of the density rho and the electrode ablation rate deltam of the graphite material;
step (3) preliminarily determining the radius R of the graphite electrodes and the distance d between the initial gas gaps formed by the pair of graphite electrodes0And initial effective height h of electrode0；
Step (4) calculating the gas gap distance d in the expected service life N by using the formula 8, wherein the invention suggests that the gas gap distance d does not exceed d after the gas switch is used for N times0Preferably 50%, otherwise returning (step 3) to increase the radius R of the graphite electrode or to increase the initial gas gap distance d0；
Step (5) calculating the effective height H of the graphite electrode in the expected service life N by using the formula 9, wherein the effective height H of the graphite electrode meets the condition that H is more than 0 after the gas switch is used for N times, otherwise, returning to the step (3) to increase the initial effective height H of the electrode0；
Step (6) calculating the self-breakdown voltage U maintained in the gas switch in the expected service life N by the formula 12bThe internal inflation pressure which needs to be set is basically unchanged, and the self-breakdown voltage U is maintained after the gas switch is used for N timesbThe substantially constant gas pressure should be a positive pressure above 101.3kPa (i.e., 1 atm), otherwise return (step 3) to increasing the radius R of the graphite electrode or increasing the initial gas gap distance d0。
And (5) finishing the key parameter design of the graphite electrode after the step (7) is finished.
The sequences of the steps (4), (5) and (6) can be interchanged.
An example of a graphite electrode design for a high energy pulse gas switch is given below:
the engineering technical requirements of a primary energy module of a certain large laser device are that an energy storage capacitor bank with total capacitance of 4400 muF is used, the energy storage capacitor bank is charged to 23.5kV voltage when in work, a graphite electrode gas switch is required to pass critical damping pulse current waves with peak value of 320kA and pulse width of 500 mus, the direct current static breakdown voltage is two times of the working voltage, namely 47kV, the temperature under the field working condition is 20 ℃, and the reliable service life of the gas switch is required to be capable of being conducted for more than 1500 times without faults under the working condition.
(step 1) from the above engineering technical requirements, the design method proposed by the present invention is now referred toNumber d0，δm，R，ρ，Q，N，P，t，UbIn the range of N ≥ 1500 times, the self-breakdown voltage Ub47kV, t 20 ℃, and the amount of single transfer charge of the switch can be calculated, i.e.:
Q＝C·U＝4400μF×23.5kV＝103.4Cb
(step 2) designing the graphite electrode by selecting a graphite electrode section bar, and supposing that a certain graphite material is selected and the density rho is 1.77g/cm3(the density of the graphite material is usually 1.7g/cm3～1.9g/cm3Middle), the electrode ablation rate δ m is 1.5 × 10-4g/Cb (either factory supplied or experimental measured), knowing these two parameters is important to electrode design, and the lower the electrode ablation rate δ m of the selected graphite material, the better.
(step 3) Next, the mechanical dimension R of the electrode, the initial gas gap distance d, is determined0And initial effective height h of electrode0The graphite electrode radius R may be 3.0cm and the initial gas gap distance d may be set00.4cm, initial effective height h of electrode0＝2.6cm。
(step 4) using a computer to calculate the numerical value, and according to the mechanical dimension parameter set in the step 3 and the formula 8, after the gas switch is used for 1500 times, the gas gap distance d is approximately equal to 1.3cm, and d is achieved03 times of 0.4cm, exceeding the 50% limit proposed by the invention, thus returning (step 3) to increasing the graphite electrode radius R or the initial gas gap distance d0Modified size R5.0 cm, d0After 1500 times of use of the gas switch, again calculated according to (equation 8), the gas gap distance d ≈ 113cm, increased by 0.33cm, i.e. 40%, meeting the 50% limit proposed by the present invention.
(step 5) after completion of step 4, the modified R is 5.0cm, d0When the value is calculated according to the formula 9 when the value is 0.8cm, the effective height H of the graphite electrode is changed from an initial value of 2.6cm to 2.4cm after the gas switch is used for 1500 times, and the condition that H is more than 0 is met.
(step 6) is finishedAfter step 5, modified R is 5.0cm, d0When the sample is equal to 0.8cm, take A0＝24.5，B0When the gas switch is used 1500 times, the self-breakdown voltage U is maintained after the gas switch is calculated by a computer according to the equation (equation 12) as 6.4bThe substantially constant air pressure of 47kV is about 1.4 standard atmospheres, meeting the requirement of the present invention of greater than 1 standard atmosphere, thus completing the design.
Therefore, in order to design the primary energy module of a large-scale laser device, the density ρ of 1.77g/cm is selected3Electrode ablation rate δ m is 1.5 × 10-4g/Cb of graphite material, the size of the gas switch can be designed to be that the radius R of the graphite electrode is 5.0cm, and the initial gas gap distance d00.8cm, initial effective height h of electrode0＝2.6cm。
The method for designing the pure graphite electrode of the high-energy pulse gas switch can grasp the requirements of key parameters under the condition of known engineering technical requirements, and scientifically and conveniently designs the corresponding graphite electrode according to steps.
The above description is a preferred embodiment of the present invention, but the present invention should not be limited to the disclosure of the embodiment and the drawings. Therefore, it is intended that all equivalents and modifications which do not depart from the spirit of the invention disclosed herein are deemed to be within the scope of the invention.
Claims (1)
1. A design method of a graphite electrode of a high-energy pulse gas switch is characterized by comprising the following steps:
step 1, determining the expected service life N times and the self-breakdown voltage U according to the engineering technical requirementsbThe unit is kV, the working temperature is t ℃, the single transfer charge quantity Q is Cb;
selecting a graphite material with the average grain diameter of less than or equal to 3 and the Shore hardness of more than or equal to 70 in the step 2, and acquiring two parameters of the density rho and the electrode ablation rate deltam of the graphite material, wherein the unit of the density rho is g/cm3Electric powerThe unit of the polar ablation rate delta m is g/Cb;
step 3, preliminarily setting the radius R of the graphite electrodes and the distance d between the initial gas gaps formed by the pair of graphite electrodes0And initial effective height h of electrode0Radius R, initial gas gap distance d0And initial effective height h of electrode0The units of (A) are all cm;
step 4, calculating the gas gap distance d in the expected service life N by using a formula I, and calculating the effective height H of the graphite electrode in the expected service life N by using a formula II; calculating the self-breakdown voltage U maintained inside the gas switch within the expected service life N using equation IIIbThe internal inflation pressure P to be set is substantially constant,
d＝d0+2 × Δ h formula I
Wherein, <math>
<mrow>
<mi>Δh</mi>
<mo>=</mo>
<mfrac>
<mrow>
<mi>N</mi>
<mo>×</mo>
<mi>δm</mi>
<mo>×</mo>
<mi>Q</mi>
</mrow>
<mrow>
<mi>π</mi>
<msup>
<mi>R</mi>
<mn>2</mn>
</msup>
<mo>×</mo>
<mi>ρ</mi>
</mrow>
</mfrac>
</mrow>
</math>
H＝h0- Δ h formula II
Wherein A is0And B0Is a constant;
step 5, judging whether the following three conditions are all met, if so, turning to step 7, otherwise, turning to step 6;
condition 1: (d-d)0)/d0Less than or equal to 50 percent;
condition 2: h is more than 0;
condition 3: p is greater than 1 standard atmosphere;
step 6, processing the conditions which are not satisfied in the step 5 according to the following requirements, and then switching to step 4: condition 1 is not satisfied, R is increased, or d is increased0(ii) a Condition 2 is not satisfied, and the initial effective height h of the electrode is increased0(ii) a If the condition 3 is not met, increasing the radius R of the graphite electrode;
and 7, designing the graphite electrode by using the obtained parameters d, H and R of the graphite electrode.
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| CN102437512B (en) * | 2011-09-09 | 2013-02-13 | 华中科技大学 | Gas switch |
| CN104079279B (en) * | 2014-06-17 | 2017-02-01 | 中国工程物理研究院流体物理研究所 | High-power gas switch trigger system |
| CN107659291B (en) * | 2017-11-01 | 2024-02-06 | 中国工程物理研究院流体物理研究所 | High-voltage pulse generator with low jitter |
| CN108767660A (en) * | 2018-05-23 | 2018-11-06 | 西北核技术研究所 | A kind of micro groove structure cathode gas spark switch |
| CN108539581B (en) * | 2018-05-23 | 2020-06-26 | 西北核技术研究所 | Metal-based graphene film cathode gas spark switch |
| CN112685894B (en) * | 2020-12-29 | 2022-06-03 | 湘潭大学 | Evaluation method for ablation resistance of electrode material of gas spark switch |
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| DE2705488A1 (en) * | 1977-02-10 | 1978-08-17 | Bosch Gmbh Robert | CONTROLLED ELECTRIC HIGH VOLTAGE SWITCHING DEVICE |
| US6630677B1 (en) * | 2001-08-29 | 2003-10-07 | Advanced Micro Devices, Inc. | Electrostatic lens having glassy graphite electrodes |
| CN101577396A (en) * | 2009-06-12 | 2009-11-11 | 西安交通大学 | Two-electrode spark gap gas switch |
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| US8785803B2 (en) * | 2007-12-21 | 2014-07-22 | Bae Systems Plc | High voltage switch |
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| DE2705488A1 (en) * | 1977-02-10 | 1978-08-17 | Bosch Gmbh Robert | CONTROLLED ELECTRIC HIGH VOLTAGE SWITCHING DEVICE |
| US6630677B1 (en) * | 2001-08-29 | 2003-10-07 | Advanced Micro Devices, Inc. | Electrostatic lens having glassy graphite electrodes |
| CN101577396A (en) * | 2009-06-12 | 2009-11-11 | 西安交通大学 | Two-electrode spark gap gas switch |
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