Pre-ionization gap design method of gas switch

Abstract

The invention particularly relates to a preionization gap design method of a gas switch, which can remarkably improve the discharge performance of a main gap of the switch and solve the problem that the existing preionization gap breakdown voltage and preionization loop energy storage capacitor capacitance value design method is difficult to reduce preionization gap main gap breakdown jitter to the greatest extent. And meanwhile, the number of main gap discharge channels of the switch is increased. According to the pre-ionization gap design method of the gas switch, three parameters which influence the breakdown performance of the pre-ionization gap, namely the pre-ionization current amplitude, the pre-ionization current pulse width and the reduced electric field at the generation moment of the pre-ionization current, and the thresholds of the parameters are fully considered, so that the influence factors considered by the design method are more comprehensive.

Description

Technical Field

[0001] This invention specifically relates to a pre-ionization gap design method for a gas switch, which can significantly improve the discharge performance of the main gap of the switch. Background Technology

[0002] In recent years, pulsed power devices have evolved towards multi-channel series or parallel configurations. Large-scale pulsed power devices with multiple series and parallel connections will include multiple drive sources and multiple triggering units, requiring the drive sources and triggering units to have stable synchronous or time-sequential operation capabilities. DC gas switches are core components of the drive sources and triggering units. Developing DC gas switches with low jitter while also considering low inductance and low trigger threshold performance has always been a crucial scientific and engineering problem to be solved in the construction of large-scale pulsed power devices.

[0003] An ultraviolet (UV) pre-ionization switch is a type of switch that incorporates a pre-ionization gap within the switch and utilizes the UV light generated by its discharge as an auxiliary ionization source. UV pre-ionization switches inherently possess advantages such as low jitter and low trigger threshold. Furthermore, the pre-ionization mechanism helps create multiple discharge channels within the UV pre-ionization gap, effectively reducing the switch inductance, mitigating electrode erosion and insulation contamination, and extending the switch's lifespan. Theoretically, it can well meet the switching requirements of large-scale pulsed power devices.

[0004] The breakdown performance of the ultraviolet pre-ionization gap has a significant impact on the operating characteristics of its main switch gap. The most direct and critical pre-ionization gap breakdown performance parameters affecting the main switch gap's operating characteristics include: pre-ionization current amplitude, pre-ionization current pulse width, and the reduced electric field at the moment the pre-ionization current is generated. The pre-ionization current amplitude relates to the initial number of electrons generated, the pre-ionization current pulse width relates to the duration and duration of initial electron generation, and the reduced electric field at the moment the pre-ionization current is generated relates to the timing of initial electron generation and the electric field strength of the main switch gap at that time.

[0005] In ultraviolet pre-ionization switches, the amplitude, pulse width, and reduced electric field at the moment of pre-ionization current generation can be adjusted by regulating the breakdown voltage of the pre-ionization gap and the capacitance of the energy storage capacitor in the pre-ionization circuit. Specifically, the breakdown voltage of the pre-ionization gap affects the reduced electric field at the moment of pre-ionization current generation (a higher breakdown voltage results in a larger reduced electric field) and also influences the amplitude of the pre-ionization current (a higher breakdown voltage results in a larger amplitude). Similarly, the energy storage capacitor in the pre-ionization circuit affects the voltage across the pre-ionization gap (a larger capacitance results in a smaller gap voltage) and the pulse width of the pre-ionization current (a larger capacitance result in a larger pulse width).

[0006] Currently, the design of the breakdown voltage of the pre-ionization gap and the capacitance value of the pre-ionization circuit energy storage capacitor in the ultraviolet pre-ionization switch is based on experimental methods. This involves conducting numerous experiments under different parameter values ​​to obtain the optimal values. This method requires a large number of experiments, has a limited range of adjustable parameters, and the experimental conclusions obtained are also somewhat limited. Therefore, there is an urgent need for an effective pre-ionization gap design method. Based on this method, the breakdown voltage of the pre-ionization gap and the capacitance value of the pre-ionization circuit energy storage capacitor should be rationally designed to minimize the breakdown jitter of the main switch gap while increasing the number of discharge channels in the main switch gap, thereby improving the breakdown performance of the pre-ionization switch gap. Summary of the Invention

[0007] The purpose of this invention is to solve the technical problem that existing design methods for pre-ionization gap breakdown voltage and pre-ionization circuit energy storage capacitor value are difficult to achieve the goal of minimizing pre-ionization main gap breakdown jitter while increasing the number of discharge channels in the main gap of the switch. This invention provides a pre-ionization gap design method for gas switches.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A method for designing a pre-ionization gap in a gas switch, characterized by the following steps:

[0010] S1. Establish calculation models for the pre-ionization discharge current parameters in relation to the breakdown jitter of the main switch gap and the number of discharge channels in the main switch gap, respectively, and obtain the pre-ionization current amplitude threshold I. c Pre-ionization current pulse width threshold t c The reduced electric field threshold (E / p) at the time of pre-ionization current generation. c The pre-ionization discharge current parameters include the pre-ionization current amplitude, the pre-ionization current pulse width, and the reduced electric field at the time of pre-ionization current generation.

[0011] S2. Set the pre-ionization gap distance to d, and obtain the pre-ionization gap breakdown voltage U through a pre-ionization gap breakdown experiment. b Linear relationship between U and air pressure p b (p);

[0012] S3. Reduce the electric field threshold (E / p) based on the actual working gas pressure p0 of the main gap and pre-ionization gap and the time of pre-ionization current generation. c The product of these two factors yields the electric field strength E of the main gap of the switch; then, based on the electric field strength E and its rising rate k... u The time t when the pre-ionization current is generated is calculated. c3 ;

[0013] S4. Based on the actual working gas pressure p0 of the pre-ionization gap and the linear relationship U...b (p), the breakdown voltage U of the pre-ionization gap under the actual working gas pressure p0 is calculated. b0 ;

[0014] S5. Establish an equivalent circuit; the equivalent circuit includes a trigger system equivalent circuit, a pre-ionization gap equivalent circuit, and a switch discharge circuit equivalent circuit connected in sequence; the pre-ionization gap equivalent circuit includes a pre-ionization circuit energy storage capacitor C. uv ;

[0015] S6. Simulate the equivalent circuit and calculate based on the pre-ionization current generation time t. c3 Breakdown voltage U b0 Pre-ionization current amplitude threshold I c Pre-ionization current pulse width threshold t c Adjusting the energy storage capacitor C in the pre-ionization circuit uv Obtain the energy storage capacitor C of the pre-ionization circuit. uv The tolerance range;

[0016] S7. Change the pre-ionization gap distance d of the gas switch, the actual working gas pressure p0, and the rate of rise k of the electric field strength E. u Following steps S2 to S6, the energy storage capacitor C of the pre-ionization circuit under different operating conditions is obtained. uv The capacitance value range; and for all pre-ionization circuit energy storage capacitors C uv The capacitance values ​​are taken from the intersection range to obtain the pre-ionization circuit energy storage capacitor C, which can take into account various different operating conditions, maintain low jitter in the main switch gap, and have a large number of discharge channels. uv The reference range for capacitance values;

[0017] S8, based on the energy storage capacitor C of the pre-ionization circuit uv The reference range for capacitance value, the field uniformity coefficient of the pre-ionization gap, and the electrode material of the pre-ionization gap are determined to complete the design of the pre-ionization gap for the gas switch.

[0018] Furthermore, step S1 specifically includes:

[0019] 1.1 Establish a calculation model for the pre-ionization discharge current parameters and the breakdown jitter of the main switch gap. Obtain the waveforms of the pre-ionization current amplitude, pre-ionization current pulse width, reduced electric field at the time of pre-ionization current generation, and the breakdown jitter of the main switch gap. Then, take the inflection points on the waveforms of the pre-ionization current amplitude, pre-ionization current pulse width, reduced electric field at the time of pre-ionization current generation, and the breakdown jitter of the main switch gap to obtain the threshold values ​​of the pre-ionization current amplitude (Ic1), the pre-ionization current pulse width (tc1), and the reduced electric field threshold (E / p)1 at the time of pre-ionization current generation that enable the main switch gap to maintain low jitter.

[0020] 1.2. Establish a calculation model for the pre-ionization discharge current parameters and the number of discharge channels in the main gap of the switch. Obtain the waveforms of the changes in the pre-ionization current amplitude, pre-ionization current pulse width, reduced electric field at the time of pre-ionization current generation, and the number of discharge channels in the main gap of the switch. Then, take the inflection points on the waveforms of the changes in the pre-ionization current amplitude, pre-ionization current pulse width, reduced electric field at the time of pre-ionization current generation, and the number of discharge channels in the main gap of the switch, and obtain the pre-ionization current amplitude threshold I that allows the main gap of the switch to maintain a large number of discharge channels. c2 Pre-ionization current pulse width threshold t c2 1. Reduce the electric field threshold (E / p)2 at the time of pre-ionization current generation;

[0021] 1.3. Based on the pre-ionization current amplitude threshold Ic1, the pre-ionization current pulse width threshold tc1, the reduced electric field threshold (E / p)1 at the pre-ionization current generation time, and the pre-ionization current amplitude threshold I... c2 Pre-ionization current pulse width threshold t c2 1. Reduce the electric field threshold (E / p)2 at the time of pre-ionization current generation, and determine the pre-ionization current amplitude threshold I. c Pre-ionization current pulse width threshold t c The reduced electric field threshold (E / p) at the time of pre-ionization current generation. c .

[0022] Furthermore, step S5 specifically includes:

[0023] 5.1 Establish the equivalent circuit of the triggering system:

[0024] The equivalent circuit of the triggering system includes energy storage capacitors C connected in series. tr Circuit inductance L tr Discharge switch S tr Trigger cable TL tr Resistor voltage divider R m and trigger isolation resistor R tr ;

[0025] The energy storage capacitor C tr Away from the loop inductor L tr One end of the trigger cable TL tr Grounding layer, resistor divider R m Keep away from trigger cable TL tr One end of each is grounded;

[0026] The trigger cable TL tr With resistor divider R m One end of the connection is connected to a trigger isolation resistor R. tr One end triggers the isolation resistor R tr The other end is connected to the equivalent circuit of the pre-ionization gap;

[0027] 5.2 Establish the equivalent circuit of the pre-ionization gap:

[0028] The equivalent circuit of the pre-ionization gap includes a pre-ionization loop inductor L connected in series. uv Pre-ionization circuit resistor R0, closed switch S uv And the pre-ionization voltage divider resistor R connected in series. uv and the pre-ionization voltage divider circuit inductor L Ruv And the pre-ionization circuit energy storage capacitor C uv The pre-ionization gap itself has a structural capacitance C0;

[0029] One end of the pre-ionization gap's own structural capacitor C0 is connected to the pre-ionization circuit inductor L. uv One end of the circuit is connected to the pre-ionization circuit resistor R0, and the other end of the pre-ionization gap's own structural capacitance C0 is connected to the closed switch S. uv The end away from where the pre-ionization circuit resistor R0 is connected;

[0030] The energy storage capacitor C in the pre-ionization circuit uv One end is connected to the pre-ionization circuit inductor L. uv At the other end, the pre-ionization voltage divider resistor R uv Inductor L, away from the pre-ionization voltage divider circuit Ruv At one end, the pre-ionization circuit energy storage capacitor C uv The other end is connected to the closed switch S. uv The end furthest from the pre-ionization circuit resistor R0 and the pre-ionization voltage divider circuit inductor L Ruv Keep away from the pre-ionization voltage divider resistor R uv One end and the equivalent circuit of the switch discharge circuit;

[0031] The trigger isolation resistor R tr The other end is connected to the pre-ionization circuit energy storage capacitor C uv One end is connected;

[0032] 5.3 Establish the equivalent circuit of the switch discharge loop:

[0033] The equivalent circuit of the switch discharge circuit includes a closed switch S1 and an energy storage capacitor C connected in series. + Circuit inductance L s Load resistance R L Energy storage capacitor C - Closed switch S2, and gap structure capacitors C1 and C2;

[0034] The gap structure capacitor C1 is connected in parallel with the closed switch S1, and the gap structure capacitor C2 is connected in parallel with the closed switch S2, which is used to simulate the two main gaps of the gas switch.

[0035] The energy storage capacitor C in the pre-ionization circuit uv The other end is connected to the connection point of closed switch S1 and closed switch S2.

[0036] Furthermore, step S6 specifically includes:

[0037] 6.1 Simulate the equivalent circuit and adjust the energy storage capacitor C of the pre-ionization loop in the equivalent circuit of the pre-ionization gap. uv The capacitance value ensures that the voltage across the pre-ionization gap is at t c3 The breakdown voltage U is reached at any time b0 At that time, the corresponding pre-ionization circuit energy storage capacitor C uv The capacitance value is the energy storage capacitor C of the pre-ionization circuit. uv The maximum value C uv1 ;

[0038] 6.2 Simulate the equivalent circuit and adjust the energy storage capacitor C of the pre-ionization loop in the equivalent circuit of the pre-ionization gap. uv The capacitance value ensures that the amplitude of the pre-ionization current flowing through the pre-ionization gap is greater than the pre-ionization current amplitude threshold I. c And its pulse width is equal to the pre-ionization current pulse width threshold t c At that time, the corresponding pre-ionization circuit energy storage capacitor C uv The capacitance value is the energy storage capacitor C of the pre-ionization circuit. uv The minimum value C uv2 .

[0039] Furthermore, step 1.3 specifically includes:

[0040] 1.3.1. Determine the threshold value I of the pre-ionization current amplitude. c1 and the pre-ionization current amplitude threshold I c2 The larger value in the range is used as the pre-ionization current amplitude threshold I to simultaneously maintain low jitter and a large number of discharge channels in the main switch gap. c ;

[0041] 1.3.2. Determine the pre-ionization current pulse width threshold t c1 and pre-ionization current pulse width threshold t c2 The larger value in the range is used as the pre-ionization current pulse width threshold t to simultaneously maintain low jitter and a large number of discharge channels in the main switch gap. c ;

[0042] 1.3.3. Take the smaller value between the reduced electric field threshold (E / p)1 and the reduced electric field threshold (E / p)2 at the time of pre-ionization current generation as the reduced electric field threshold (E / p) at the time of pre-ionization current generation to simultaneously maintain low jitter and a large number of discharge channels in the main gap of the switch. c .

[0043] The beneficial effects of this invention are:

[0044] 1. The method of the present invention fully considers the three parameters and their thresholds that affect the breakdown performance of the pre-ionization gap: the pre-ionization current amplitude, the pre-ionization current pulse width, and the reduced electric field at the moment of pre-ionization current generation, making the influencing factors considered in this design method more comprehensive.

[0045] 2. The method of the present invention is simpler and more effective, avoiding the disadvantages of traditional methods such as large experimental workload, limited range of parameter values, and limited experimental conclusions.

[0046] 3. The method of the present invention can significantly reduce the breakdown jitter of the main gap of the switch by rationally designing the breakdown voltage of the pre-ionization gap and the capacitance value of the energy storage capacitor of the pre-ionization circuit, while increasing the number of discharge channels of the main gap of the switch. Attached Figure Description

[0047] Figure 1 This is a flowchart of an embodiment of the method of the present invention;

[0048] Figure 2 This is a waveform diagram showing the changes in the pre-ionization current amplitude and the breakdown jitter of the main switch gap in the embodiment of the method of the present invention;

[0049] Figure 3 This is a waveform diagram showing the changes in the pre-ionization current pulse width and the breakdown jitter of the main switch gap in the embodiment of the method of the present invention;

[0050] Figure 4 This is a waveform diagram showing the changes in the reduced electric field and the breakdown jitter of the main gap of the switch at the moment of pre-ionization current generation in an embodiment of the method of the present invention.

[0051] Figure 5 This is a waveform diagram showing the change in the pre-ionization current amplitude and the number of discharge channels in the main gap of the switch in an embodiment of the method of the present invention;

[0052] Figure 6 This is a waveform diagram showing the variation of the pre-ionization current pulse width and the number of discharge channels in the main gap of the switch in an embodiment of the method of the present invention;

[0053] Figure 7 This is a waveform diagram showing the change in the reduced electric field and the number of discharge channels in the main gap of the switch at the moment of pre-ionization current generation in an embodiment of the method of the present invention.

[0054] Figure 8 This is a schematic diagram of the equivalent circuit established in the embodiment of the method of the present invention. Detailed Implementation

[0055] like Figure 1 As shown, a pre-ionization gap design method for a gas switch, taking an ultraviolet pre-ionization field distortion gas switch composed of an anode, a cathode, and a trigger electrode as an example, includes the following steps:

[0056] Step 1: Establish calculation models for the pre-ionization discharge current parameters in relation to the breakdown jitter of the main switch gap and the number of discharge channels in the main switch gap, respectively, and obtain the pre-ionization current amplitude threshold I. c Pre-ionization current pulse width threshold t c The reduced electric field threshold (E / p) at the time of pre-ionization current generation. c ;

[0057] 1.1 Establish a calculation model for the pre-ionization discharge current parameters and the breakdown jitter of the main gap of the switch. Obtain the change waveforms of the pre-ionization current amplitude, pre-ionization current pulse width, reduced electric field at the time of pre-ionization current generation (i.e., the reduced electric field of the main gap at the time of pre-ionization current generation) and the breakdown jitter of the main gap of the switch. Then, take the inflection points on the change waveforms of the pre-ionization current amplitude, pre-ionization current pulse width, reduced electric field at the time of pre-ionization current generation and the breakdown jitter of the main gap of the switch, and obtain the pre-ionization current amplitude threshold Ic1, pre-ionization current pulse width threshold tc1, and reduced electric field threshold (E / p)1 at the time of pre-ionization current generation to maintain low jitter of the main gap of the switch.

[0058] In this embodiment, based on the ultraviolet pre-ionization photoelectric effect and breakdown probability theory, a calculation model for the pre-ionization discharge current parameters and the breakdown jitter of the main gap of the switch is established using Matlab software programming, which yields... Figure 2 , Figure 3 and Figure 4 The waveforms of the pre-ionization current amplitude, pre-ionization current pulse width, reduced electric field at the moment of pre-ionization current generation, and breakdown jitter of the main switch gap are obtained respectively. From these waveforms, the pre-ionization current amplitude threshold I that maintains low jitter in the main switch gap is obtained. c1 40A, pre-ionization current pulse width threshold t c1 The reduced electric field threshold (E / p) at the time of pre-ionization current generation is 33 kV / MPa·mm, with a time of 6 ns.

[0059] 1.2. Establish a calculation model for the pre-ionization discharge current parameters and the number of discharge channels in the main gap of the switch. Obtain the waveforms of the changes in the pre-ionization current amplitude, pre-ionization current pulse width, reduced electric field at the time of pre-ionization current generation, and the number of discharge channels in the main gap of the switch. Then, take the inflection points on the waveforms of the changes in the pre-ionization current amplitude, pre-ionization current pulse width, reduced electric field at the time of pre-ionization current generation, and the number of discharge channels in the main gap of the switch, and obtain the pre-ionization current amplitude threshold I that allows the main gap of the switch to maintain a large number of discharge channels. c2 Pre-ionization current pulse width threshold t c2 1. Reduce the electric field threshold (E / p)2 at the time of pre-ionization current generation;

[0060] In this embodiment, based on the modified Martin multi-channel discharge theory, a calculation model for the pre-ionization discharge current parameters and the number of discharge channels in the main gap of the switch is established using Matlab software programming, resulting in the following: Figure 5 , Figure 6 and Figure 7 The waveforms showing the changes in pre-ionization current amplitude, pre-ionization current pulse width, reduced electric field at the moment of pre-ionization current generation, and the number of discharge channels in the main gap of the switch are presented. From these waveforms, the pre-ionization current amplitude threshold I that maintains a relatively large number of discharge channels in the main gap of the switch is obtained. c2 30A, pre-ionization current pulse width threshold t c2 The reduced electric field threshold (E / p)2 at the time of pre-ionization current generation is 36 kV / MPa·mm, with a time limit of 8 ns.

[0061] 1.3. Based on the pre-ionization current amplitude threshold Ic1, the pre-ionization current pulse width threshold tc1, the reduced electric field threshold (E / p)1 at the pre-ionization current generation time, and the pre-ionization current amplitude threshold I... c2 Pre-ionization current pulse width threshold t c2 1. Reduce the electric field threshold (E / p)2 at the time of pre-ionization current generation, and determine the pre-ionization current amplitude threshold I. c Pre-ionization current pulse width threshold t c The reduced electric field threshold (E / p) at the time of pre-ionization current generation. c ;

[0062] 1.3.1. Determine the threshold value I of the pre-ionization current amplitude. c1 and the pre-ionization current amplitude threshold I c2 The larger value in the range is used as the pre-ionization current amplitude threshold I to simultaneously maintain low jitter and a large number of discharge channels in the main switch gap. c ;

[0063] 1.3.2. Determine the pre-ionization current pulse width threshold t c1 and pre-ionization current pulse width threshold t c2 The larger value in the range is used as the pre-ionization current pulse width threshold t to simultaneously maintain low jitter and a large number of discharge channels in the main switch gap. c ;

[0064] 1.3.3. Take the smaller value between the reduced electric field threshold (E / p)1 and the reduced electric field threshold (E / p)2 at the time of pre-ionization current generation as the reduced electric field threshold (E / p) at the time of pre-ionization current generation to simultaneously maintain low jitter and a large number of discharge channels in the main gap of the switch. c .

[0065] In this embodiment, the pre-ionization current amplitude threshold I c Take the pre-ionization current amplitude threshold I c1 and the pre-ionization current amplitude threshold I c2 The larger value is 40A. Pre-ionization current pulse width threshold t c Take the pre-ionization current pulse width threshold t c1 and pre-ionization current pulse width threshold t c2 The larger value is 8 ns. The reduced electric field threshold (E / p) at the time of pre-ionization current generation. c The smaller of the reduced electric field threshold (E / p)1 at the time of pre-ionization current generation and the reduced electric field threshold (E / p)2 at the time of pre-ionization current generation is taken as 33kV / Mpa·mm.

[0066] Step 2: Set the pre-ionization gap distance to d, and obtain the pre-ionization gap breakdown voltage U under the condition of this pre-ionization gap distance d through a pre-ionization gap breakdown experiment. b Linear relationship between U and air pressure p b (p).

[0067] In this embodiment, the pre-ionization gap distance d is 2mm, and the pre-ionization gap breakdown voltage U is obtained experimentally. b The linear relationship between U and air pressure p satisfies: b = 25.377p + 2.115, where the breakdown voltage U b The units for pressure p are kV and MPa, respectively.

[0068] Step 3: Reduce the electric field threshold (E / p) based on the actual working gas pressure p0 of the main gap and pre-ionization gap and the time of pre-ionization current generation. c The product of these two factors yields the electric field strength E of the main gap of the switch; then, based on the electric field strength E and its rising rate k... u The time t when the pre-ionization current is generated is calculated. c3 ;

[0069] In this embodiment, the operating voltage of the main switch gap is 80kV, and the spacing between the main switch gaps is 10mm. The actual operating gas pressure p0 of the main switch gap and the pre-ionization gap is 0.529MPa. The reduced electric field threshold (E / p) at the moment of pre-ionization current generation is calculated. c The corresponding electric field strength E of the main gap of the switch is 17.457 kV / mm; the rate of rise k of the electric field strength E of the main gap of the switch is... u The value is 0.9 kV / (mm·ns), and the time t when the pre-ionization current is generated is calculated. c3 It is 10.51 ns.

[0070] Step 4: Based on the actual working gas pressure p0 of the pre-ionization gap and the breakdown voltage U of the pre-ionization gap.b Linear relationship between U and air pressure p b (p), the breakdown voltage U of the pre-ionization gap under the actual working gas pressure p0 is calculated. b0 .

[0071] In this embodiment, the actual working gas pressure p0 of the pre-ionization gap is 0.529 MPa. According to the formula, U... b =25.377p + 2.115, the breakdown voltage U of the pre-ionization gap is calculated. b0 It is 15.54kV.

[0072] Step 5, as follows Figure 8 As shown, an equivalent circuit is established, which includes a trigger system equivalent circuit, a pre-ionization gap equivalent circuit, and a switch discharge circuit equivalent circuit connected in sequence.

[0073] 5.1 Establishing the equivalent circuit of the triggering system: The equivalent circuit of the triggering system includes energy storage capacitors C connected in series. tr (1nF), circuit inductance L tr (120nH), Discharge switch S tr Trigger cable TL tr (50Ω), resistor divider R m and trigger isolation resistor R tr (500Ω); Energy storage capacitor C tr Away from the loop inductor L tr One end of the trigger cable TL tr Grounding layer, resistor divider R m Keep away from trigger cable TL tr One end of the trigger cable is grounded; tr With resistor divider R m One end of the connection is connected to a trigger isolation resistor R. tr One end triggers the isolation resistor R tr The other end is connected to the equivalent circuit of the pre-ionization gap;

[0074] 5.2 Establishing the equivalent circuit of the pre-ionization gap: The equivalent circuit of the pre-ionization gap includes the pre-ionization loop inductor L connected in series. uv (100nH), pre-ionization circuit resistance R0 (0.05Ω), closed switch S uv And the pre-ionization voltage divider resistor R connected in series. uv (1MΩ) and pre-ionization voltage divider circuit inductance L Ruv (100nH), and the pre-ionization circuit energy storage capacitor C uv The pre-ionization gap itself has a structural capacitance C0 (0.02pF);

[0075] One end of the pre-ionization gap's own structural capacitor C0 is connected to the pre-ionization circuit inductor L. uv One end of the circuit is connected to the pre-ionization circuit resistor R0, and the other end of the pre-ionization gap's own structural capacitance C0 is connected to the closed switch S. uv The end furthest from the pre-ionization circuit resistor R0; the pre-ionization circuit energy storage capacitor C uv One end is connected to the pre-ionization circuit inductor L. uv At the other end, the pre-ionization voltage divider resistor R uv Inductor L, away from the pre-ionization voltage divider circuit Ruv At one end, the pre-ionization circuit energy storage capacitor C uv The other end is connected to the closed switch S. uv The end furthest from the pre-ionization circuit resistor R0 and the pre-ionization voltage divider circuit inductor L Ruv Keep away from the pre-ionization voltage divider resistor R uv One end and the equivalent circuit of the switch discharge circuit; trigger isolation resistor R tr The other end is connected to the pre-ionization circuit energy storage capacitor C uv One end is connected;

[0076] 5.3 Establishing the equivalent circuit of the switch discharge circuit: The equivalent circuit of the switch discharge circuit includes a closed switch S1 connected in series and an energy storage capacitor C. + (40nF), circuit inductance L s (180nH), load resistance R L (3Ω), Energy storage capacitor C - (40nF), closed switch S2, and gap structure capacitors C1 (2pF) and C2 (2pF); gap structure capacitor C1 is connected in parallel with closed switch S1, and gap structure capacitor C2 is connected in parallel with closed switch S2, used to simulate the two main gaps of the gas switch; pre-ionization circuit energy storage capacitor C uv The other end is connected to the connection point of closed switch S1 and closed switch S2.

[0077] S6. Simulate the equivalent circuit and calculate based on the pre-ionization current generation time t. c3 Breakdown voltage U b0 Pre-ionization current amplitude threshold I c Pre-ionization current pulse width threshold t c Adjusting the energy storage capacitor C in the pre-ionization circuit uv Obtain the energy storage capacitor C of the pre-ionization circuit. uv The tolerance range;

[0078] 6.1 Simulate the equivalent circuit and adjust the energy storage capacitor C of the pre-ionization loop in the equivalent circuit of the pre-ionization gap. uv The capacitance value ensures that the voltage across the pre-ionization gap is constant at the moment the pre-ionization current is generated (t). c3Reaching breakdown voltage U b0 At that time, the corresponding pre-ionization circuit energy storage capacitor C uv The capacitance value is the energy storage capacitor C of the pre-ionization circuit. uv The maximum value C uv1 ;

[0079] In this embodiment, the equivalent circuit is simulated, and the voltage across the pre-ionization gap is calculated at the time t when the pre-ionization current is generated. c3 The breakdown voltage U is reached at (10.51 ns). b0 The pre-ionization circuit energy storage capacitor C at (15.54kV) uv The maximum value C uv1 The capacitance is 21.0pF.

[0080] 6.2 Simulate the equivalent circuit and adjust the energy storage capacitor C of the pre-ionization loop in the equivalent circuit of the pre-ionization gap. uv The capacitance value ensures that the amplitude of the pre-ionization current flowing through the pre-ionization gap is greater than the pre-ionization current amplitude threshold I. c And its pulse width is equal to the pre-ionization current pulse width threshold t c At that time, the corresponding pre-ionization circuit energy storage capacitor C uv The capacitance value is the energy storage capacitor C of the pre-ionization circuit. uv The minimum value C uv2 ;

[0081] In this embodiment, the simulated equivalent circuit is configured such that the amplitude of the pre-ionization current flowing through the pre-ionization gap is greater than the pre-ionization current amplitude threshold I. c (40A) and its pulse width is equal to the pre-ionization current pulse width threshold t. c At (8ns), the energy storage capacitor C of the pre-ionization circuit uv The minimum value C uv2 Its capacitance is 10.2pF.

[0082] Step 7: Based on the actual operating conditions of the gas switch, change the pre-ionization gap distance d, the actual operating gas pressure p0, and the rate of rise k of the electric field strength E. u Following steps S2 to S6, the energy storage capacitor C of the pre-ionization circuit under different operating conditions is obtained. uv The capacitance value range; and for all pre-ionization circuit energy storage capacitors C uv The capacitance values ​​are taken from the intersection range to obtain the pre-ionization circuit energy storage capacitor C, which can take into account various different operating conditions, maintain low jitter in the main switch gap, and have a large number of discharge channels. uv The range of capacitance values;

[0083] Following steps S2 to S6, the operating voltage of the main gap of the switch is obtained to be 60–80 kV, and the rate of increase k of the electric field strength E of the main gap of the switch is determined.u Under the conditions of 5.2~9.0kV / ns, a pre-ionization gap distance d of 0.5~2mm, and an actual working gas pressure p0 of 0.415~0.529Mpa, the reference range for the value of the energy storage capacitor in the pre-ionization circuit that simultaneously maintains low jitter and a large number of discharge channels in the main switch gap is 10.3~17.6pF.

[0084] S8, based on the energy storage capacitor C of the pre-ionization circuit uv The reference range for capacitance value, the field uniformity coefficient of the pre-ionization gap, and the electrode material of the pre-ionization gap are determined to complete the design of the pre-ionization gap for the gas switch.

[0085] In this embodiment, the pre-ionization gap of the gas switch is structurally designed. The field uniformity coefficient of the pre-ionization gap (the ratio of the maximum electric field strength to the average electric field strength) is set within the range of 2.2 to 3.0 to ensure that the pre-ionization gap itself has good breakdown stability. The electrode material constituting the pre-ionization gap is selected as a material with low work function, good ablation resistance, and a large proportion of discharge ultraviolet spectrum distribution.

[0086] The pre-ionization circuit energy storage capacitor consists of a coaxial ring structure formed by the pre-ionization needle of the gas switch, the trigger electrode, and a ceramic resistor. Modeling and simulation were performed using CST software. The outer diameter of the coaxial ring structure (i.e., the outer diameter of the ceramic resistor) is 6 mm, the inner diameter of the coaxial ring structure (i.e., the inner diameter of the pre-ionization needle) is 2 mm, and the length of the coaxial ring structure is 15 mm. The dielectric constant of the resistor substrate material is 16. At this point, the capacitance of the pre-ionization circuit energy storage capacitor is 11.3 pF, which is within its reference capacitance range. Simultaneously, the field uniformity coefficient of the pre-ionization gap is 2.8, and the electrode material is copper-impregnated graphite.

[0087] Experimental results show that, according to the pre-ionization gap design method of the gas switch of the present invention, the breakdown jitter of the main gap of the switch can be less than 1 ns, and the number of discharge channels can be greater than 3, demonstrating the significant advantages of low jitter and a large number of discharge channels.

Claims

1. A method for designing a pre-ionization gap in a gas switch, characterized in that, Includes the following steps: S1. Establish calculation models for the pre-ionization discharge current parameters in relation to the breakdown jitter of the main switch gap and the number of discharge channels in the main switch gap, respectively, and obtain the pre-ionization current amplitude threshold I. c Pre-ionization current pulse width threshold t c The reduced electric field threshold (E / p) at the time of pre-ionization current generation. c The pre-ionization discharge current parameters include the pre-ionization current amplitude, the pre-ionization current pulse width, and the reduced electric field at the time of pre-ionization current generation. S2. Set the pre-ionization gap distance to d, and obtain the pre-ionization gap breakdown voltage U through a pre-ionization gap breakdown experiment. b Linear relationship between U and air pressure p b (p); S3. Reduce the electric field threshold (E / p) based on the actual working gas pressure p0 of the main gap and pre-ionization gap and the time of pre-ionization current generation. c The product of these two values ​​yields the electric field strength E in the main gap of the switch. Then, based on the electric field strength E and its rate of rise k u The time t when the pre-ionization current is generated is calculated. c3 ; S4. Based on the actual working gas pressure p0 of the pre-ionization gap and the linear relationship U... b (p), the breakdown voltage U of the pre-ionization gap under the actual working gas pressure p0 is calculated. b0 ; S5. Establish an equivalent circuit; the equivalent circuit includes a trigger system equivalent circuit, a pre-ionization gap equivalent circuit, and a switch discharge circuit equivalent circuit connected in sequence; the pre-ionization gap equivalent circuit includes a pre-ionization circuit energy storage capacitor C. uv ; S6. Simulate the equivalent circuit and calculate based on the pre-ionization current generation time t. c3 Breakdown voltage U b0 Pre-ionization current amplitude threshold I c Pre-ionization current pulse width threshold t c Adjusting the energy storage capacitor C in the pre-ionization circuit uv Obtain the energy storage capacitor C of the pre-ionization circuit. uv The tolerance range; S7. Change the pre-ionization gap distance d of the gas switch, the actual working gas pressure p0, and the rate of rise k of the electric field strength E. u Following steps S2 to S6, the energy storage capacitor C of the pre-ionization circuit under different operating conditions is obtained. uv The capacitance value range; and for all pre-ionization circuit energy storage capacitors C uv The capacitance values ​​are taken from the intersection range to obtain the pre-ionization circuit energy storage capacitor C, which can take into account various different operating conditions, maintain low jitter in the main switch gap, and have a large number of discharge channels. uv The reference range for capacitance values; S8, based on the energy storage capacitor C of the pre-ionization circuit uv The reference range for capacitance value, the field uniformity coefficient of the pre-ionization gap, and the electrode material of the pre-ionization gap are determined to complete the design of the pre-ionization gap for the gas switch.

2. The pre-ionization gap design method for the gas switch according to claim 1, characterized in that, Step S1 is as follows: 1.1 Establish a calculation model for the pre-ionization discharge current parameters and the breakdown jitter of the main switch gap. Obtain the waveforms of the pre-ionization current amplitude, pre-ionization current pulse width, reduced electric field at the time of pre-ionization current generation, and the breakdown jitter of the main switch gap. Then, take the inflection points on the waveforms of the pre-ionization current amplitude, pre-ionization current pulse width, reduced electric field at the time of pre-ionization current generation, and the breakdown jitter of the main switch gap to obtain the threshold values ​​of the pre-ionization current amplitude (Ic1), the pre-ionization current pulse width (tc1), and the reduced electric field threshold (E / p)1 at the time of pre-ionization current generation that enable the main switch gap to maintain low jitter. 1.

2. Establish a calculation model for the pre-ionization discharge current parameters and the number of discharge channels in the main gap of the switch. Obtain the waveforms of the changes in the pre-ionization current amplitude, pre-ionization current pulse width, reduced electric field at the time of pre-ionization current generation, and the number of discharge channels in the main gap of the switch. Then, take the inflection points on the waveforms of the changes in the pre-ionization current amplitude, pre-ionization current pulse width, reduced electric field at the time of pre-ionization current generation, and the number of discharge channels in the main gap of the switch, and obtain the pre-ionization current amplitude threshold I that allows the main gap of the switch to maintain a large number of discharge channels. c2 Pre-ionization current pulse width threshold t c2 1. Reduce the electric field threshold (E / p)2 at the time of pre-ionization current generation; 1.

3. Based on the pre-ionization current amplitude threshold Ic1, the pre-ionization current pulse width threshold tc1, the reduced electric field threshold (E / p)1 at the pre-ionization current generation time, and the pre-ionization current amplitude threshold I... c2 Pre-ionization current pulse width threshold t c2 1. Reduce the electric field threshold (E / p)2 at the time of pre-ionization current generation, and determine the pre-ionization current amplitude threshold I. c Pre-ionization current pulse width threshold t c The reduced electric field threshold (E / p) at the time of pre-ionization current generation. c .

3. The pre-ionization gap design method for the gas switch according to claim 2, characterized in that, Step S5 is as follows: 5.1 Establish the equivalent circuit of the triggering system: The equivalent circuit of the triggering system includes energy storage capacitors C connected in series. tr , circuit inductance L tr Discharge switch S tr Trigger cable TL tr Resistor voltage divider R m and trigger isolation resistor R tr ; The energy storage capacitor C tr Away from the loop inductor L tr One end of the trigger cable TL tr Grounding layer, resistor divider R m Keep away from trigger cable TL tr One end of each is grounded; The trigger cable TL tr With resistor divider R m One end of the connection is connected to a trigger isolation resistor R. tr One end triggers the isolation resistor R tr The other end is connected to the equivalent circuit of the pre-ionization gap; 5.2 Establish the equivalent circuit of the pre-ionization gap: The equivalent circuit of the pre-ionization gap includes a pre-ionization loop inductor L connected in series. uv Pre-ionization circuit resistor R0, closed switch S uv And the pre-ionization voltage divider resistor R connected in series. uv and the pre-ionization voltage divider circuit inductor L Ruv And the pre-ionization circuit energy storage capacitor C uv The pre-ionization gap itself has a structural capacitance C0; One end of the pre-ionization gap's own structural capacitor C0 is connected to the pre-ionization circuit inductor L. uv One end of the circuit is connected to the pre-ionization circuit resistor R0, and the other end of the pre-ionization gap's own structural capacitance C0 is connected to the closed switch S. uv The end away from where the pre-ionization circuit resistor R0 is connected; The energy storage capacitor C in the pre-ionization circuit uv One end is connected to the pre-ionization circuit inductor L. uv At the other end, the pre-ionization voltage divider resistor R uv Inductor L, away from the pre-ionization voltage divider circuit Ruv At one end, the pre-ionization circuit energy storage capacitor C uv The other end is connected to the closed switch S. uv The end furthest from the pre-ionization circuit resistor R0 and the pre-ionization voltage divider circuit inductor L Ruv Keep away from the pre-ionization voltage divider resistor R uv One end and the equivalent circuit of the switch discharge circuit; The trigger isolation resistor R tr The other end is connected to the pre-ionization circuit energy storage capacitor C uv One end is connected; 5.3 Establish the equivalent circuit of the switch discharge loop: The equivalent circuit of the switch discharge circuit includes a closed switch S1 and an energy storage capacitor C connected in series. + , circuit inductance L s Load resistance R L Energy storage capacitor C - Closed switch S2, and gap structure capacitors C1 and C2; The gap structure capacitor C1 is connected in parallel with the closed switch S1, and the gap structure capacitor C2 is connected in parallel with the closed switch S2, which is used to simulate the two main gaps of the gas switch. The energy storage capacitor C in the pre-ionization circuit uv The other end is connected to the connection point of closed switch S1 and closed switch S2.

4. The pre-ionization gap design method for the gas switch according to claim 3, characterized in that, Step S6 is as follows: 6.1 Simulate the equivalent circuit and adjust the energy storage capacitor C of the pre-ionization loop in the equivalent circuit of the pre-ionization gap. uv The capacitance value ensures that the voltage across the pre-ionization gap is at t c3 The breakdown voltage U is reached at any time b0 At that time, the corresponding pre-ionization circuit energy storage capacitor C uv The capacitance value is the energy storage capacitor C of the pre-ionization circuit. uv The maximum value C uv1 ; 6.2 Simulate the equivalent circuit and adjust the energy storage capacitor C of the pre-ionization loop in the equivalent circuit of the pre-ionization gap. uv The capacitance value ensures that the amplitude of the pre-ionization current flowing through the pre-ionization gap is greater than the pre-ionization current amplitude threshold I. c And its pulse width is equal to the pre-ionization current pulse width threshold t c At that time, the corresponding pre-ionization circuit energy storage capacitor C uv The capacitance value is the energy storage capacitor C of the pre-ionization circuit. uv The minimum value C uv2 .

5. The pre-ionization gap design method for the gas switch according to claim 4, characterized in that, Step 1.3 specifically involves: 1.3.

1. Determine the threshold value I of the pre-ionization current amplitude. c1 and the pre-ionization current amplitude threshold I c2 The larger value in the range is used as the pre-ionization current amplitude threshold I to simultaneously maintain low jitter and a large number of discharge channels in the main switch gap. c ; 1.3.

2. Determine the pre-ionization current pulse width threshold t c1 and pre-ionization current pulse width threshold t c2 The larger value in the range is used as the pre-ionization current pulse width threshold t to simultaneously maintain low jitter and a large number of discharge channels in the main switch gap. c ; 1.3.

3. Take the smaller value between the reduced electric field threshold (E / p)1 and the reduced electric field threshold (E / p)2 at the time of pre-ionization current generation as the reduced electric field threshold (E / p) at the time of pre-ionization current generation to simultaneously maintain low jitter and a large number of discharge channels in the main gap of the switch. c .

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