Cold cathode trigger tube circuit simulation SPICE model design method

Abstract

The invention belongs to the technical field of cold cathode trigger tubes, and discloses a cold cathode trigger tube circuit simulation SPICE design method, which comprises the following steps: designing a main gap channel; designing a trigger gap channel; designing a control module; carrying out characteristic parameter verification and problem analysis on the cold cathode trigger tube; a cold cathode trigger tube SPICE model is improved based on the gas discharge theory, and characteristic parameters are verified; the invention relates to application simulation and result analysis of an improved cold cathode trigger tube. The cold cathode trigger tube SPICE model provided by the invention meets the functions of a modern cold cathode trigger tube, simulation verification is carried out on the cold cathode trigger tube, and different parameters of the model can be modified to meet the requirements of different scenes.

Description

Technical Field

[0001] The invention belongs to the technical field of cold cathode trigger tubes, and in particular relates to a cold cathode trigger tube circuit simulation SPICE design method. Background Art

[0002] As a type of triggered spark gap switch, the cold cathode trigger tube has some characteristics that cannot be replaced by other types of devices. It has a wide range of applications, mainly as a high-voltage pulse switch for various high-voltage pulse generators, aircraft engine ignition, and protection of high-voltage equipment and components. However, there is currently no complete, simple and reliable SPICE model. Summary of the invention

[0003] In view of the problems existing in the prior art, the present invention provides a cold cathode trigger tube circuit simulation SPICE design method.

[0004] The present invention is implemented as follows: a cold cathode trigger tube circuit simulation SPICE design method, the method comprising: S1: Main gap channel design; S2: Trigger gap channel design; S3: control module design; S4: Verification of characteristic parameters of cold cathode trigger tube and analysis of problems; S5: Improvement of the SPICE model of cold cathode trigger tube and verification of characteristic parameters based on gas discharge theory; S6: Improved cold cathode trigger tube application simulation and result analysis.

[0005] Further, the S1 specifically includes: Under specific trigger conditions, when an external working voltage is applied to both ends of the main gap channel, the cold cathode trigger tube as a whole will exhibit a working state or a non-working state depending on the size and direction of the external voltage. When the cold cathode trigger tube is in a non-working state, the main gap channel will exhibit a large insulation resistance, generally above 10MΩ, while the resistance of the main gap channel of the trigger tube after conduction is reduced to a few tenths of an ohm, which is close to a short-circuit state.

[0006] Further, the S2 specifically includes: Under normal circumstances, when the voltage applied at both ends of the main gap channel is lower than the self-breakdown voltage of the trigger tube, the trigger tube will not break down and conduct. At this time, if a trigger pulse with a certain amplitude and width is applied to the trigger electrode, the trigger gap between the trigger electrode and the adjacent electrode will break down and conduct, generating discharge. The discharge process is also the breakdown and conduction of the trigger tube. Due to the interference of external uncertain factors, in order to avoid mis-conduction of the trigger tube, it is necessary to set the minimum trigger current I Tkmin .

[0007] Further, the S3 specifically includes: (1) Self-breakdown voltage control module The self-breakdown voltage of the cold cathode trigger tube is mainly affected by many factors such as the type and pressure of the gas in the tube, the gap distance between adjacent electrodes, the electrode material, size, shape and electrode surface condition. A formula for calculating the self-breakdown voltage of the cold cathode trigger tube based on three parameters: ionization constant, gap distance between adjacent electrodes and gas pressure in the trigger tube:

[0008] Where: a is the gas constant; e is the gap distance between adjacent electrodes in the trigger tube; p is the gas pressure in the trigger tube; The output voltages of three different DC voltage sources are used to replace the above three parameters to realize the input of parameters and the calculation of self-breakdown voltage; (2) Working voltage control module A trigger pulse with a certain amplitude and width is applied, and the required working voltage is calculated from the general working characteristic curve of the cold cathode trigger tube. However, the general working characteristic curve of the actual cold cathode trigger tube is difficult to express in the form of a mathematical function. (3) Working current limiting module According to the general working characteristic curve of the cold cathode trigger tube, when a larger working voltage is applied, a larger working current will appear in the main gap channel circuit, while the general cold cathode trigger tube has a limited working current range; when the main gap current is less than the maximum working current I opmax When , the voltage at the node Open closes the voltage-controlled switch S_Open, and the entire main gap channel is closed, so that the cold cathode trigger tube can work normally.

[0009] Further, the S4 specifically includes: (1) Self-breakdown voltage test Connect the tube to be tested, and slowly increase the DC voltage applied to both ends of the main gap within the specified voltage rise time until the main gap breaks down, and record the breakdown voltage value, which is the self-breakdown voltage value of the trigger tube; (2) Self-breakdown voltage test Connect the tube to be tested, add the specified working voltage to both ends of the main gap, gradually increase the trigger voltage to make the trigger tube work, and record the voltage value of the DC voltage of the trigger tube at this time, which is the minimum trigger voltage of the trigger tube; (3) Working voltage range test Connect the tube to be tested, and under the specified triggering conditions, gradually increase the DC voltage applied to both ends of the main gap to make the trigger tube work, and record the DC voltage value, which is the minimum working voltage of the trigger tube; (4) Working current range test Connect the tube to be tested, apply the specified trigger voltage and working voltage, make the trigger tube work normally, and measure the maximum working current value.

[0010] Further, the S5 specifically includes: (1) Gap switch control; (2) Channel resistance; (3) Channel inductance; (4) Model verification and parameter setting.

[0011] Further, the step (1) comprises: The breakdown of the gas discharge switch is equivalent to the closing of the voltage-controlled switch S_Ch. The closing of S_Ch is controlled by the voltage source B_Ch_On, and its output is determined by the logic composed of V(Delay_Over) and V(Maintain). If either V(Delay_Over) or V(Maintain) is greater than 0.5V, the output of B_Ch_On is 1V, and the switch S_Ch is turned on. The existence of the resistor R1 and the capacitor C1 provides a limited time for the node voltage V(Ch_On) to rise, thereby ensuring that the transition time of the switch S_Ch is limited. Breakdown Delay: The node voltage V(Delay_Over) is determined by the behavior voltage source B_Dly_Ovr, and its output is a logic decision formula. If the node voltage V(T_Over) is greater than V(delay), it is true, the output jumps to 1V, and the switch S_Ch is closed; these two nodes represent the time when the gap voltage exceeds the static breakdown voltage and the breakdown delay time respectively; The time when the gap voltage exceeds the static breakdown voltage is represented by the voltage at the node T_Over, which is generated by the behavioral voltage source B_T_Ovr, and its output is the simulation time minus the voltage value of the node T_B, in seconds; when V(Over) is greater than 0.5V, B_! Ovr drops from 1V to 0V, and switch S1 is turned off, freezing the voltage of C2 and thus freezing the voltage of node T_B; the voltage value of node Over is generated by voltage source B_Ovr, and its output is an IF judgment statement. If the gap voltage is greater than the static breakdown voltage, the output is 1V, otherwise it remains 0V; here, when the IF statement judgment condition is true, the result uses the tanh function to smooth the transition of switch S1 from the off state to the on state to avoid discontinuities that prevent the convergence of the simulation solution; the size of the gap voltage is represented by the voltage at the node V_Gap, which is generated by the behavioral voltage source B_V_Gap, and its output is the absolute value of the voltage difference between nodes T1 and T2; the static breakdown voltage is represented by the voltage at the node V_Break, which is generated by the behavioral voltage source B_V_Brk, and its output uses the following formula, which is applicable to very small gaps under high voltage, and the unit is kV;

[0012] The breakdown delay time is the time from when the gas discharge switch exceeds the static breakdown voltage to when the switch is closed and the channel is turned on. It is expressed as the voltage at the node delay and is generated by the behavioral voltage source B_Dly. Its output is determined by Martin's empirical formula and the unit is s.

[0013] Where: E is the gap electric field, in kV / cm, calculated at node E_Gap, generated by the behavioral voltage source B_E_Gap, and its output is the ratio of the node voltage V_Gap to the channel spacing D; ρ is the gap gas volume density, in g / cm3, calculated at node Rho_V, generated by the behavioral voltage source B_Rho, and its output is related to the gap gas pressure and atmospheric pressure; Channel holding current: After the switch S_Ch is initially closed, the gap voltage will drop rapidly, and the current will begin to fill the entire loop. In order to maintain the continuity of the closure of the switch S_Ch, it is assumed that there is a minimum current value. When the channel current is greater than the minimum value, there is no need to consider the breakdown delay problem. The switch will continue to be closed, and B_Ch_On will maintain the output of 1V; the minimum current value is represented by the node I_Min, which is generated by the DC voltage source B_I_Min. When the channel current I_Ch is greater than the minimum value, the V (Maintain) output is 1V; the channel current I_Ch is represented by the voltage at the node I_Ch, which is generated by the behavioral current source B_I_Ch, and its output is the absolute value of the channel current; Further, the step (2) comprises: The output of the voltage source B_Res is the product of the current passing through itself and the voltage at the node R_Ch, which represents the channel gap resistance after the gas discharge switch is broken down, in Ω; a formula for calculating the channel resistance based on three parameters: gap distance, channel radius and channel current:

[0014] Where c is the proportionality constant given by 876, d is the gap distance, i is the channel current, and r is the calculated channel radius in m;

[0015] Where i is the channel current in kA, t is the channel formation time in μs, and ρ is the gap gas density in g / cm 3; The formula is used by the current source B_Ch_Rad to drive the voltage at the node Ch_Rad to represent the channel radius; D4 limits the charging of C5 to the peak output of B_Ch_Rad, which is then attenuated by R3. This combination exists because the derivation of the channel radius calculation formula proposed by Braginskii only considers the pulse-driven channel growth and does not ignore any contraction or dissipation; at the same time, when the channel is not conducting, a switch controlled by the Ch_On node voltage can be used to keep C6 discharged; Braginskii's channel radius expression requires the time after the arc is formed as an input variable; therefore, a circuit is added to the model to calculate the time of the last transition of the switch S_Ch from off to on; this time is represented by the voltage at the node T_Arc and is generated in the same way as the overvoltage time described above, using the logical inverse of the node Ch_On voltage as the control signal of the sample and hold circuit, which determines the arc start time at the node T_C.

[0016] Furthermore, the step (3) specifically includes: In the main circuit, the closed channel inductance is modeled by a behavioral current source B_Ind. After the voltage across the inductor is converted into a current through B_Ind, the current is integrated through capacitor C4, and the result of the integration generates a voltage at the node Int_V_L in units of V∙S×109. Then the current generated by B_Ind is set to the voltage at Int_V_L divided by the voltage at L_Ch to represent the channel inductance in nH. The voltage at the node L_Ch is generated by the voltage source B_L_Ch, and its output uses the inductance expression of an isolated thin line in units of nH.

[0017] Where: d is the gap distance, in cm; r is the channel radius, in m; The output of the voltage source B_L_Ch uses a limiting function limit. This is because when the inductance is too small, the output of the voltage source B_Ind will reach infinity. For a smaller channel radius, an upper limit is set so that the inductance is not too large.

[0018] Furthermore, the step (4) specifically includes: A trigger voltage with a certain amplitude and a certain width is applied to activate switches S3 and S4. Capacitors C7 and C8 have initial voltages of the same magnitude but opposite directions. When the switches are activated, capacitors C7 and C8 begin to discharge. Lossy transmission line Rg218 is used to simulate the same type of coaxial cable connecting the pulse transmitter and the test unit.

[0019] In combination with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows: First, the cold cathode trigger tube SPICE model proposed in the present invention meets the functions of modern cold cathode trigger tubes and has been simulated and verified. In addition, the model can modify different parameters to meet the needs of different scenarios.

[0020] The present invention has carried out model design, characteristic parameter testing, improvement and simulation verification for cold cathode trigger tube under the simulation software LTspice. The present invention proposes and studies a new SPICE model of cold cathode trigger tube. Under the set parameters, its self-breakdown voltage is 15.51kV, the minimum trigger voltage is 3.00kV, the working voltage range is 7.03-10.00kV, and the working current is less than 7.14kA. All characteristic parameters meet the detailed specifications of RQ-10 cold cathode trigger tube. In view of the self-breakdown phenomenon and the uncontrollable conduction delay time, two improved cold cathode trigger tube models (type I and type II) are designed. The gas discharge switch used is constructed based on the gas discharge principle. When the pulse arrives at the measuring unit at the same time, a voltage approximately equal to 3.5 times the initial charging voltage of the capacitor appears on the switch. The time for the pulse to reach the switch is about 3ns, the peak duration is about 8ns, and the rise and fall times are both about 8ns. In order to verify the correctness of the two types of improved cold cathode trigger tubes, the parameter characteristics of the two improved types were simulated and verified as above, and the results were similar to the various characteristic parameters of the model before improvement. In order to verify the universality of the two types of improved cold cathode trigger tubes, the two improved cold cathode trigger tube models were simulated in three mainstream circuit simulation software Ltspice, Multisim and Pspice: under the external working voltage of 16kV, 18kV and 20kV, the improved cold cathode trigger tube (type I) can effectively suppress the occurrence of self-breakdown phenomenon; for the improved cold cathode trigger tube (type II), the effects of gap distance, gas pressure and gap voltage on the conduction delay time were simulated respectively. The simulation results show that the conduction delay time is proportional to the gap distance and gas pressure, and inversely proportional to the gap voltage. Under the parameter conditions set by the present invention, the conduction delay time ranges from 81.30ns to 481.71ns.

[0021] Second, the cold cathode trigger tube SPICE model proposed in the present invention meets the functions of modern cold cathode trigger tubes, and has been simulated and verified, and the model can modify different parameters to meet the needs of different scenarios. In response to some problems found in the simulation and verification process, an improved cold cathode trigger tube model (type I) and an improved cold cathode trigger tube model (type II) are proposed based on the gas discharge principle. These two improved models effectively solve the self-breakdown phenomenon and uncontrollable conduction delay time problems of traditional cold cathode trigger tubes. At the same time, application simulation verification has been carried out in three mainstream circuit simulation software, LTspice, Multisim and Pspice. The simulation results further verify the universality of the model established by the present invention, which has strong feasibility and lays a foundation for subsequent research work.

[0022] Third, as auxiliary evidence of the inventiveness of the claims of the present invention, it is also reflected in the following important aspects: (1) The expected benefits and commercial value of the technical solution of the present invention after transformation are: (2) The technical solution of the present invention fills the technical gap in the industry at home and abroad: (3) Whether the technical solution of the present invention solves the technical problems that people have been eager to solve but have never been able to solve successfully: (4) Whether the technical solution of the present invention overcomes technical bias: BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The main gap channel circuit provided by the embodiment of the present invention; Figure 2 A trigger gap channel circuit provided by an embodiment of the present invention; Figure 3 A self-breakdown voltage control module provided by an embodiment of the present invention; Figure 4 is a general characteristic curve of a cold cathode trigger tube provided by an embodiment of the present invention; Figure 5 is an approximate processing polyline provided by an embodiment of the present invention; Figure 6 It is a minimum trigger voltage control module provided by an embodiment of the present invention; Figure 7 It is a working current limiting module provided by an embodiment of the present invention; Figure 8 is a self-breakdown voltage test circuit diagram provided by an embodiment of the present invention; Fig. 9 It is a self-breakdown voltage test simulation waveform diagram provided by an embodiment of the present invention; Fig.10 is a minimum trigger voltage test circuit diagram provided by an embodiment of the present invention; Fig.11 This is a simulation waveform diagram of the minimum trigger voltage test provided by an embodiment of the present invention; Fig.12 This is a simulation waveform diagram of the minimum operating voltage test provided by an embodiment of the present invention; Fig.13 is the highest working voltage test simulation waveform provided by the embodiment of the present invention; Fig.14 It is a working current range test simulation waveform provided by an embodiment of the present invention; Fig.15 The main circuit of the gas discharge switch provided by the embodiment of the present invention; Fig.16 is a gap switch control module provided by an embodiment of the present invention; Fig.17 A channel resistance calculation module provided by an embodiment of the present invention; Fig.18 A gas discharge switch verification circuit provided by an embodiment of the present invention; Fig.19 is a gas discharge switch verification waveform provided by an embodiment of the present invention; Fig. 20 A self-breakdown suppression module provided by an embodiment of the present invention; Fig.21 It is a static breakdown voltage weakening module provided by an embodiment of the present invention; Fig. 22 It is an improved cold cathode trigger tube model (type I) (main gap channel) provided by an embodiment of the present invention; Fig.23 It is an improved cold cathode trigger tube model (type II) (trigger gap channel) provided by an embodiment of the present invention; Fig.24 It is a self-breakdown voltage test simulation waveform diagram provided by an embodiment of the present invention; Fig.25 This is a simulation waveform diagram of the minimum trigger voltage test provided by an embodiment of the present invention; Fig.26 This is a simulation waveform diagram of the minimum operating voltage test provided by an embodiment of the present invention; Fig. 27 It is a simulation waveform diagram of the highest working voltage test provided by an embodiment of the present invention; Fig.28 It is a simulation waveform diagram of the working current range test provided by an embodiment of the present invention; Fig.29 The improved cold cathode trigger tube model (Type I) self-breakdown suppression effect provided by the embodiment of the present invention is (a) self-breakdown suppression effect (16kV); (b) self-breakdown suppression effect (18kV); (c) self-breakdown suppression effect (20kV). DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0025] An embodiment of the present invention provides a cold cathode trigger tube circuit simulation SPICE design method, the method comprising: S1: Main gap channel design; S2: Trigger gap channel design; S3: control module design; S4: Verification of characteristic parameters of cold cathode trigger tube and analysis of problems; S5: Improvement of the SPICE model of cold cathode trigger tube and verification of characteristic parameters based on gas discharge theory; S6: Improved cold cathode trigger tube application simulation and result analysis.

[0026] The S1 specifically includes: Under specific trigger conditions, when an external working voltage is applied to both ends of the main gap channel, the cold cathode trigger tube as a whole will exhibit a working state or a non-working state depending on the size and direction of the external voltage. When the cold cathode trigger tube is in a non-working state, the main gap channel will exhibit a large insulation resistance, generally above 10MΩ, while the resistance of the main gap channel of the trigger tube after conduction is reduced to a few tenths of an ohm, which is close to a short-circuit state. Figure 1 In the figure, R_On and R_Off represent the channel resistance of the main gap channel in the working state and the non-working state respectively, C_On and L_On represent the distributed capacitance and distributed inductance of the main gap channel in the conducting state respectively, C_Off and L_Off represent the distributed capacitance and distributed inductance of the main gap channel in the non-conducting state respectively; the output voltages of the behavioral voltage sources B_E_FwBreak and B_E_ReBreak represent the forward and reverse breakdown threshold voltages respectively, the output voltage of the behavioral voltage source B_E_On represents the working voltage of the main gap channel, D1, D2 and D3 serve as branch switches of the three branches; the voltage-controlled switch S_Open is used to limit the working current of the main gap channel.

[0027] The S2 specifically includes: Under normal circumstances, when the voltage applied at both ends of the main gap channel is lower than the self-breakdown voltage of the trigger tube, the trigger tube will not break down and conduct. At this time, if a trigger pulse with a certain amplitude and width is applied to the trigger electrode, the trigger gap between the trigger electrode and the adjacent electrode will break down and conduct, generating discharge. The discharge process is also the breakdown and conduction of the trigger tube. Due to the interference of external uncertain factors, in order to avoid mis-conduction of the trigger tube, it is necessary to set the minimum trigger current I Tkmin. Figure 2 In the example, W1 acts as a flow control switch. When the current in the trigger gap channel is greater than I Tkmin When the switch is closed, the trigger pulse can reach the adjacent electrode. R_Tk, C_Tk and L_Tk represent the distributed resistance, distributed inductance and distributed capacitance of the trigger gap channel circuit respectively.

[0028] Further, the S3 specifically includes: (1) Self-breakdown voltage control module The self-breakdown voltage of the cold cathode trigger tube is mainly affected by many factors such as the type and pressure of the gas in the tube, the gap distance between adjacent electrodes, the electrode material, size, shape and electrode surface condition. A formula for calculating the self-breakdown voltage of the cold cathode trigger tube based on three parameters: ionization constant, gap distance between adjacent electrodes and gas pressure in the trigger tube:

[0029] Where: a is the gas constant; e is the gap distance between adjacent electrodes in the trigger tube; p is the gas pressure in the trigger tube; The output voltages of three different DC voltage sources are used to replace the above three parameters to realize the input of parameters and the calculation of self-breakdown voltage; Figure 3 As shown, R_A, R_D and R_P represent the series internal resistance of the three DC voltage sources respectively.

[0030] (2) Working voltage control module A trigger pulse with a certain amplitude and width is applied, and the required working voltage is calculated from the general working characteristic curve of the cold cathode trigger tube. However, the general working characteristic curve of the actual cold cathode trigger tube is difficult to express in the form of a mathematical function; Figure 4 Here, we use the TBL current source in LTspice to simulate the characteristic curve. According to the requirements of the TBL current source, it is impossible to use the same input to get different outputs. Here, we make an approximation to the general characteristic curve of the cold cathode trigger tube, that is, we take as many key node data as possible to clamp several points of the curve, and get the following Figure 5 The relationship line shown.

[0031] like Figure 6As shown, the behavior voltage source B_Tril provides the absolute value of the external trigger voltage for the current source G_Omin in the form of TBL, so that G_Omin outputs a current with the same value as the corresponding working voltage VAK in the cold cathode trigger tube approximate processing line, and the resistor R_Omin is the equivalent series internal resistance of B_Tril and G_Omin. The voltage value of the node Tmin is generated by the behavior voltage source B_Tmin, representing the set minimum trigger voltage VTmin. The voltage of the node Ctrl is generated by the behavior voltage source B_Ctrl, and its output uses the IF judgment statement.

[0032] (3) Working current limiting module like Figure 7 As shown, according to the general working characteristic curve of the cold cathode trigger tube, when a larger working voltage is applied, a larger working current will appear in the main gap channel circuit, while the general cold cathode trigger tube has a limited working current range; when the main gap current is less than the maximum working current I opmax When , the voltage at the node Open closes the voltage-controlled switch S_Open, and the entire main gap channel is closed, so that the cold cathode trigger tube can work normally.

[0033] The S4 specifically includes: (1) Self-breakdown voltage test like Figure 8 As shown, connect the tube to be tested, slowly increase the DC voltage applied to both ends of the main gap within the specified voltage rise time until the main gap breaks down, and record the breakdown voltage value, which is the self-breakdown voltage value of the trigger tube; set the output voltage of the behavioral voltage source B_Open to be 1V, so that the voltage-controlled switch S_Open is continuously closed. The voltage source V3 generates a pulse voltage with an initial value of 0, a peak value of 30kV, a delay time of 0s, a rise time of 50ns, a duration of 0s, and a fall time of 50ns. CTT is the established cold cathode trigger tube equivalent model. The measurement of the main gap channel current is equivalent to measuring the current flowing through the resistor R_On. The simulation waveform is shown as follows Fig. 9 shown.

[0034] (2) Self-breakdown voltage test like Fig.10 As shown, connect the tube to be tested, add the specified working voltage at both ends of the main gap, gradually increase the trigger voltage to make the trigger tube work, and record the voltage value of the DC voltage of the trigger tube at this time, which is the minimum trigger voltage of the trigger tube; the voltage source V3 generates a constant DC voltage with an amplitude of 9kV, and the voltage source V4 generates a pulse voltage with an initial value of 0, a peak value of 30kV, a delay time of 0s, a rise time of 50ns, a duration of 0s, and a fall time of 50ns. The simulation waveform is as follows Fig.11 shown.

[0035] (3) Working voltage range test according to Fig.10 Connect the tube to be tested. Under the specified triggering conditions, gradually increase the DC voltage applied to both ends of the main gap to make the trigger tube work, and record the DC voltage value, which is the minimum working voltage of the trigger tube; the voltage source V3 generates a pulse voltage with an initial value of 0, a peak value of 10kV, a delay time of 0s, a rise time of 50ns, a duration of 0s, and a fall time of 50ns. The voltage source V4 generates a constant DC voltage with an amplitude of 20kV. The simulation waveform is as follows: Fig.12 shown.

[0036] According to the test results, the minimum trigger voltage of the trigger tube WTmin = 3.00kV. If the output of the DC voltage source V4 is changed so that its output is slightly greater than WTmin, the output peak of the voltage source V3 changes to 15kV. The moment when the trigger tube starts working is recorded, and the DC voltage value is also recorded, which is the maximum operating voltage of the trigger tube.

[0037] (4) Working current range test according to Fig.10 Connect the tube under test, apply the specified trigger voltage and working voltage, make the trigger tube work normally, and measure the maximum working current value. Voltage source V3 generates a pulse voltage with an initial value of 0, a peak value of 15kV, a delay time of 0s, a rise time of 50ns, a duration of 150ns, and a fall time of 10ns. Voltage source V4 generates a pulse voltage with an initial value of 0, a peak value of 20kV, a delay time of 0s, a rise time of 50ns, a duration of 0s, and a fall time of 50ns. The simulation waveform is as follows: Fig.14 shown.

[0038] Further, the S5 specifically includes: The basic circuit of the gas discharge switch consists of four basic components, among which T1 and T2 are used as the input and output terminals of the external power supply, the behavioral current source B_Ind is used to represent the distributed inductance of the channel, the voltage-controlled switch S_Ch controls the conduction and disconnection of the channel, and the behavioral voltage source B_Res is used to represent the distributed resistance of the channel. The above three components are connected in series and in parallel with C_Gap, which is used to represent the distributed capacitance of the channel. The basic circuit structure is as follows Fig.15 shown.

[0039] (1) Gap switch control; (2) Channel resistance; (3) Channel inductance; (4) Model verification and parameter setting.

[0040] Further, if Fig.16 As shown, the step (1) comprises: The breakdown of the gas discharge switch is equivalent to the closing of the voltage-controlled switch S_Ch. The closing of S_Ch is controlled by the voltage source B_Ch_On, and its output is determined by the logic composed of V(Delay_Over) and V(Maintain). If either V(Delay_Over) or V(Maintain) is greater than 0.5V, the output of B_Ch_On is 1V, and the switch S_Ch is turned on. The existence of the resistor R1 and the capacitor C1 provides a limited time for the node voltage V(Ch_On) to rise, thereby ensuring that the transition time of the switch S_Ch is limited. Breakdown Delay: The node voltage V(Delay_Over) is determined by the behavior voltage source B_Dly_Ovr, and its output is a logic decision formula. If the node voltage V(T_Over) is greater than V(delay), it is true, the output jumps to 1V, and the switch S_Ch is closed; these two nodes represent the time when the gap voltage exceeds the static breakdown voltage and the breakdown delay time respectively; The time when the gap voltage exceeds the static breakdown voltage is represented by the voltage at the node T_Over, which is generated by the behavioral voltage source B_T_Ovr, and its output is the simulation time minus the voltage value of the node T_B, in seconds; when V(Over) is greater than 0.5V, B_! Ovr drops from 1V to 0V, and switch S1 is turned off, freezing the voltage of C2 and thus freezing the voltage of node T_B; the voltage value of node Over is generated by voltage source B_Ovr, and its output is an IF judgment statement. If the gap voltage is greater than the static breakdown voltage, the output is 1V, otherwise it remains 0V; here, when the IF statement judgment condition is true, the result uses the tanh function to smooth the transition of switch S1 from the off state to the on state to avoid discontinuities that prevent the convergence of the simulation solution; the size of the gap voltage is represented by the voltage at the node V_Gap, which is generated by the behavioral voltage source B_V_Gap, and its output is the absolute value of the voltage difference between nodes T1 and T2; the static breakdown voltage is represented by the voltage at the node V_Break, which is generated by the behavioral voltage source B_V_Brk, and its output uses the following formula, which is applicable to very small gaps under high voltage, and the unit is kV;

[0041] The breakdown delay time is the time from when the gas discharge switch exceeds the static breakdown voltage to when the switch is closed and the channel is turned on. It is expressed as the voltage at the node delay and is generated by the behavioral voltage source B_Dly. Its output is determined by Martin's empirical formula and the unit is s.

[0042] Where: E is the gap electric field, in kV / cm, calculated at node E_Gap, generated by the behavioral voltage source B_E_Gap, and its output is the ratio of the node voltage V_Gap to the channel spacing D; ρ is the gap gas volume density, in g / cm3, calculated at node Rho_V, generated by the behavioral voltage source B_Rho, and its output is related to the gap gas pressure and atmospheric pressure; Channel holding current: After the switch S_Ch is initially closed, the gap voltage will drop rapidly, and the current will begin to fill the entire loop. In order to maintain the continuity of the closure of the switch S_Ch, it is assumed that there is a minimum current value. When the channel current is greater than the minimum value, there is no need to consider the breakdown delay problem. The switch will continue to be closed, and B_Ch_On will maintain the output of 1V; the minimum current value is represented by the node I_Min, which is generated by the DC voltage source B_I_Min. When the channel current I_Ch is greater than the minimum value, the V (Maintain) output is 1V; the channel current I_Ch is represented by the voltage at the node I_Ch, which is generated by the behavioral current source B_I_Ch, and its output is the absolute value of the channel current; like Fig.17 As shown, the step (2) includes: The output of the voltage source B_Res is the product of the current passing through itself and the voltage at the node R_Ch, which represents the channel gap resistance after the gas discharge switch is broken down, in Ω; a formula for calculating the channel resistance based on three parameters: gap distance, channel radius and channel current:

[0043] Where c is the proportionality constant given by 876, d is the gap distance, i is the channel current, and r is the calculated channel radius in m;

[0044] Where i is the channel current in kA, t is the channel formation time in μs, and ρ is the gap gas density in g / cm 3; The formula is used by the current source B_Ch_Rad to drive the voltage at the node Ch_Rad to represent the channel radius; D4 limits the charging of C5 to the peak output of B_Ch_Rad, which is then attenuated by R3. This combination exists because the derivation of the channel radius calculation formula proposed by Braginskii only considers the pulse-driven channel growth and does not ignore any contraction or dissipation; at the same time, when the channel is not conducting, a switch controlled by the Ch_On node voltage can be used to keep C6 discharged; Braginskii's channel radius expression requires the time after the arc is formed as an input variable; therefore, a circuit is added to the model to calculate the time of the last transition of the switch S_Ch from off to on; this time is represented by the voltage at the node T_Arc and is generated in the same way as the overvoltage time described above, using the logical inverse of the node Ch_On voltage as the control signal of the sample and hold circuit, which determines the arc start time at the node T_C.

[0045] The step (3) specifically includes: In the main circuit, the closed channel inductance is modeled by a behavioral current source B_Ind. After the voltage across the inductor is converted into a current through B_Ind, the current is integrated through capacitor C4, and the result of the integration generates a voltage at the node Int_V_L in units of V∙S×109. Then the current generated by B_Ind is set to the voltage at Int_V_L divided by the voltage at L_Ch to represent the channel inductance in nH. The voltage at the node L_Ch is generated by the voltage source B_L_Ch, and its output uses the inductance expression of an isolated thin line in units of nH.

[0046] Where: d is the gap distance, in cm; r is the channel radius, in m; The output of the voltage source B_L_Ch uses a limiting function limit. This is because when the inductance is too small, the output of the voltage source B_Ind will reach infinity. For a smaller channel radius, an upper limit is set so that the inductance is not too large.

[0047] The step (4) specifically includes: like Fig.18 As shown, a trigger voltage with a certain amplitude and a certain width is applied to activate switches S3 and S4. Capacitors C7 and C8 have initial voltages of the same magnitude but opposite directions. When the switch is activated, capacitors C7 and C8 begin to discharge. The lossy transmission line Rg218 is used to simulate the same type of coaxial cable connecting the pulse transmitter and the test unit.

[0048] like Fig.19As shown, when the pulses arrive at the measuring unit at the same time, a voltage approximately equal to 3.5 times the initial charging voltage of the capacitor appears on the switch, the time it takes for the pulses to arrive at the gas discharge switch is approximately 3ns, the peak duration is approximately 8ns, and the rise and fall times are both approximately 8ns.

[0049] like Fig. 20 As shown, when the input voltage is greater than the self-breakdown voltage of the cold cathode trigger tube, the gap channel will not be turned on. In theory, no current will pass through the main gap channel of the cold cathode trigger tube, thereby suppressing the self-breakdown phenomenon of the cold cathode trigger tube.

[0050] like Fig.21 As shown, the principle is to introduce a weakening coefficient r. The existence of r makes the gap voltage always greater than the static breakdown voltage. At the same time, the output voltage of the node Over becomes a judgment whether the voltage of the node V_Gap is greater than the weakened static breakdown voltage V_Break_End, thereby ensuring that the switch can be broken down and turned on.

[0051] like Fig. 22 As shown; the gas discharge switch main circuit and the static breakdown voltage weakening module are added to the cold cathode trigger tube trigger gap channel circuit and the gas discharge switch control module respectively to realize the function of controlling the cold cathode trigger tube conduction delay time, as shown Fig.23 shown.

[0052] Referring to the cold cathode trigger tube test method of the electronic industry standard of the People's Republic of China, the characteristic parameter test and verification of the constructed improved cold cathode trigger tube SPICE model is carried out. In the simulation, the verification circuit and parameter settings are the same as Section 3. In the improved cold cathode trigger tube model (Type I), the distributed capacitance C of the gas discharge switch is set to 1pF, and the types of diodes D1, D2, and D3 are MBR0520L, 1N5817, and ideal diodes, respectively; in the improved cold cathode trigger tube model (II), the distributed capacitance C of the gas discharge switch is set to 100nF, and the types of diodes D1, D2, and D3 are all 1N5817, and the attenuation coefficient r is set to 0.1. The simulation waveforms of various characteristic parameter tests are shown in the figure. Figure 24-28 shown.

[0053] A specific implementation scheme of an embodiment of the present invention, the working principle of the cold cathode trigger tube circuit simulation SPICE design method can be described in detail as follows: 1. Main gap channel design (S1): In the SPICE simulation environment, the main gap channel needs to be designed first. The main gap channel is the main part of the cold cathode trigger tube and determines the basic electrical characteristics of the trigger tube.

[0054] The electrical parameters of the main gap, such as breakdown voltage, discharge current, etc., need to be considered during the design process. These parameters will directly affect the performance of the trigger tube.

[0055] 2. Trigger gap channel design (S2): The trigger gap channel is a channel in the cold cathode trigger tube used to trigger the main gap discharge.

[0056] When designing the trigger gap channel, it is necessary to determine parameters such as the trigger voltage and trigger current to ensure that the main gap discharge can be reliably triggered under given conditions.

[0057] 3. Control module design (S3): The control module is used to control the working status of the main gap and the trigger gap.

[0058] In SPICE simulation, the control module can be implemented through programming to adjust the electrical parameters of the main gap and the trigger gap, such as voltage, current, etc., according to the actual needs of the circuit.

[0059] 4. Verification of characteristic parameters and problem analysis of cold cathode trigger tube (S4): After completing the design of the main gap channel, trigger gap channel and control module, the characteristic parameters of the cold cathode trigger tube need to be verified.

[0060] The circuit model is run through SPICE simulation software to observe and record the electrical characteristics of the trigger tube, such as trigger voltage, trigger current, discharge delay time, etc.

[0061] If you find that the simulation results do not match expectations or there are problems, you need to analyze the reasons and make corresponding adjustments.

[0062] 5. Improved SPICE model and characteristic parameter verification of cold cathode trigger tube based on gas discharge theory (S5): According to the gas discharge theory, the SPICE model of cold cathode trigger tube is improved.

[0063] When improving the model, it is necessary to consider the physical phenomena and electrical characteristics of the gas discharge process, such as gas ionization, electron generation and transmission, etc.

[0064] By improving the model, the electrical characteristics of the cold cathode trigger tube can be simulated more accurately.

[0065] The improved model needs to be verified by SPICE simulation software to ensure the accuracy and reliability of the simulation results.

[0066] 6. Improved cold cathode trigger tube application simulation and result analysis (S6): The improved cold cathode trigger tube SPICE model is applied to the actual circuit for simulation analysis.

[0067] The working state of the circuit is simulated by simulation software, and the performance of the trigger tube in the actual circuit is observed and recorded.

[0068] Analyze the simulation results to evaluate whether the performance of the trigger tube meets the design requirements, and make further optimization and adjustments as needed.

[0069] In short, this cold cathode trigger tube circuit simulation SPICE design method provides effective tools and methods for the design and optimization of cold cathode trigger tubes through detailed steps and principles. Through the application of SPICE simulation software, the electrical characteristics of cold cathode trigger tubes can be simulated and analyzed more accurately, providing strong support for circuit design and optimization.

[0070] The specific implementation method of the cold cathode trigger tube circuit simulation SPICE design method can be carried out by referring to the following steps: 1. Preliminary preparation 1. Understand the working principle of cold cathode trigger tube: Cold cathode trigger tube uses the principle of gas discharge and has the characteristics of high reliability and strong environmental adaptability. It is widely used in military, medical, aviation and scientific research fields.

[0071] 2. Familiarity with SPICE software: SPICE is a circuit-level simulation program developed by the University of California, Berkeley, USA, suitable for nonlinear DC, transient and linear AC analysis.

[0072] 2. Model Design 1. Main gap channel design: According to the working principle of the cold cathode trigger tube, the electrical parameters of the main gap, such as breakdown voltage, discharge current, etc., are determined.

[0073] In SPICE, the main gap channel is simulated by editing and modifying existing models or creating new models.

[0074] 2. Trigger gap channel design: The design of the trigger gap channel needs to ensure that the main gap discharge can be reliably triggered under given conditions.

[0075] Set the trigger voltage, trigger current and other parameters, and simulate the trigger gap channel in SPICE.

[0076] 3. Control module design: A control module is designed to control the working status of the main gap and the trigger gap.

[0077] In SPICE, the functions of the control module, such as adjusting voltage and current, are implemented through programming.

[0078] 3. Model Verification and Improvement 1. Verification of characteristic parameters of cold cathode trigger tube: Use SPICE simulation software to run the circuit model and observe and record the electrical characteristics of the trigger tube, such as trigger voltage, trigger current, discharge delay time, etc.

[0079] Compare simulation results with expected values ​​or experimental data to ensure the accuracy of the simulation model.

[0080] 2. Improved model based on gas discharge theory: According to the gas discharge theory, the physical phenomena and electrical characteristics of the cold cathode trigger tube during the discharge process are analyzed.

[0081] According to the analysis results, the SPICE model is improved to simulate the electrical characteristics of the cold cathode trigger tube more accurately.

[0082] 3. Verify the characteristic parameters again: The improved model is used for simulation to verify the electrical characteristics of the trigger tube again.

[0083] Ensure that the improved model can more accurately reflect the performance of cold cathode trigger tubes.

[0084] 4. Application simulation and result analysis 1. Apply the improved model to the actual circuit: The improved cold cathode trigger tube SPICE model is embedded into the actual circuit.

[0085] The working state of the circuit is simulated in SPICE, and the performance of the trigger tube in the actual circuit is observed and recorded.

[0086] 2. Result analysis: Analyze the simulation results and evaluate whether the performance of the trigger tube meets the design requirements.

[0087] If the performance does not meet the requirements, further optimization and adjustment are carried out according to the simulation results.

[0088] Through the above steps, the specific operation of the cold cathode trigger tube circuit simulation SPICE design method can be realized. In the whole process, it is necessary to ensure the accuracy of the model, the reliability of the simulation results and the rationality of the optimization adjustment.

[0089] It should be noted that the embodiments of the present invention can be implemented by hardware, software, or a combination of software and hardware. The hardware part can be implemented using dedicated logic; the software part can be stored in a memory and executed by an appropriate instruction execution system, such as a microprocessor or dedicated design hardware. It can be understood by a person of ordinary skill in the art that the above-mentioned devices and methods can be implemented using computer executable instructions and / or contained in a processor control code, such as a carrier medium such as a disk, CD or DVD-ROM, a programmable memory such as a read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. Such code is provided on the carrier medium. The device and its modules of the present invention can be implemented by hardware circuits such as very large-scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, etc., or programmable hardware devices such as field programmable gate arrays, programmable logic devices, etc., can also be implemented by software executed by various types of processors, and can also be implemented by a combination of the above-mentioned hardware circuits and software, such as firmware.

[0090] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A cold cathode trigger tube circuit simulation SPICE design method, characterized in that: The method includes: S1: Main gap channel design; S2: Trigger gap channel design; S3: control module design; S4: Verification of characteristic parameters of cold cathode trigger tube and analysis of problems; S5: Improvement of the SPICE model of cold cathode trigger tube and verification of characteristic parameters based on gas discharge theory; S6: Improved cold cathode trigger tube application simulation and result analysis.

2. The cold cathode trigger tube circuit simulation SPICE design method as claimed in claim 1, characterized in that: The S1 specifically includes: Under specific trigger conditions, when an external working voltage is applied to both ends of the main gap channel, the cold cathode trigger tube as a whole will exhibit a working state or a non-working state depending on the size and direction of the external voltage. When the cold cathode trigger tube is in a non-working state, the main gap channel will exhibit a large insulation resistance, generally above 10MΩ, while the resistance of the main gap channel of the trigger tube after conduction is reduced to a few tenths of an ohm, which is close to a short-circuit state.

3. The cold cathode trigger tube circuit simulation SPICE design method as claimed in claim 1, characterized in that: The S2 specifically includes: Under normal circumstances, when the voltage applied at both ends of the main gap channel is lower than the self-breakdown voltage of the trigger tube, the trigger tube will not break down and conduct. At this time, if a trigger pulse with a certain amplitude and width is applied to the trigger electrode, the trigger gap between the trigger electrode and the adjacent electrode will break down and conduct, generating discharge. The discharge process is also the breakdown and conduction of the trigger tube. Due to the interference of external uncertain factors, in order to avoid mis-conduction of the trigger tube, it is necessary to set the minimum trigger current I Tkmin .

4. The cold cathode trigger tube circuit simulation SPICE design method as claimed in claim 1, characterized in that: The S3 specifically includes: (1) Self-breakdown voltage control module The self-breakdown voltage of the cold cathode trigger tube is mainly affected by many factors such as the type and pressure of the gas in the tube, the gap distance between adjacent electrodes, the electrode material, size, shape and electrode surface condition. A formula for calculating the self-breakdown voltage of the cold cathode trigger tube based on three parameters: ionization constant, gap distance between adjacent electrodes and gas pressure in the trigger tube: Where: a is the gas constant; e is the gap distance between adjacent electrodes in the trigger tube; p is the gas pressure in the trigger tube; The output voltages of three different DC voltage sources are used to replace the above three parameters to realize the input of parameters and the calculation of self-breakdown voltage; (2) Working voltage control module A trigger pulse with a certain amplitude and width is applied, and the required working voltage is calculated from the general working characteristic curve of the cold cathode trigger tube. However, the general working characteristic curve of the actual cold cathode trigger tube is difficult to express in the form of a mathematical function. (3) Working current limiting module According to the general working characteristic curve of the cold cathode trigger tube, when a larger working voltage is applied, a larger working current will appear in the main gap channel circuit, while the general cold cathode trigger tube has a limited working current range; when the main gap current is less than the maximum working current I opmax When , the voltage at the node Open closes the voltage-controlled switch S_Open, and the entire main gap channel is closed, so that the cold cathode trigger tube can work normally.

5. The cold cathode trigger tube circuit simulation SPICE design method as claimed in claim 1, characterized in that: The S4 specifically includes: (1) Self-breakdown voltage test Connect the tube to be tested, and slowly increase the DC voltage applied to both ends of the main gap within the specified voltage rise time until the main gap breaks down, and record the breakdown voltage value, which is the self-breakdown voltage value of the trigger tube; (2) Self-breakdown voltage test Connect the tube to be tested, add the specified working voltage to both ends of the main gap, gradually increase the trigger voltage to make the trigger tube work, and record the voltage value of the DC voltage of the trigger tube at this time, which is the minimum trigger voltage of the trigger tube; (3) Working voltage range test Connect the tube to be tested, and under the specified triggering conditions, gradually increase the DC voltage applied to both ends of the main gap to make the trigger tube work, and record the DC voltage value, which is the minimum working voltage of the trigger tube; (4) Working current range test Connect the tube to be tested, apply the specified trigger voltage and working voltage, make the trigger tube work normally, and measure the maximum working current value.

6. The cold cathode trigger tube circuit simulation SPICE design method as claimed in claim 1, characterized in that: The S5 specifically includes: (1) Gap switch control; (2) Channel resistance; (3) Channel inductance; (4) Model verification and parameter setting.

7. The cold cathode trigger tube circuit simulation SPICE design method as claimed in claim 6, characterized in that: The step (1) comprises: The breakdown of the gas discharge switch is equivalent to the closing of the voltage-controlled switch S_Ch. The closing of S_Ch is controlled by the voltage source B_Ch_On, and its output is determined by the logic composed of V(Delay_Over) and V(Maintain). If either V(Delay_Over) or V(Maintain) is greater than 0.5V, the output of B_Ch_On is 1V, and the switch S_Ch is turned on. The existence of the resistor R1 and the capacitor C1 provides a limited time for the node voltage V(Ch_On) to rise, thereby ensuring that the transition time of the switch S_Ch is limited. Breakdown Delay: The node voltage V(Delay_Over) is determined by the behavior voltage source B_Dly_Ovr, and its output is a logic decision formula. If the node voltage V(T_Over) is greater than V(delay), it is true, the output jumps to 1V, and the switch S_Ch is closed; these two nodes represent the time when the gap voltage exceeds the static breakdown voltage and the breakdown delay time respectively; The time when the gap voltage exceeds the static breakdown voltage is represented by the voltage at the node T_Over, which is generated by the behavioral voltage source B_T_Ovr, and its output is the simulation time minus the voltage value of the node T_B, in seconds; when V(Over) is greater than 0.5V, B_! Ovr drops from 1V to 0V, and switch S1 is turned off, freezing the voltage of C2 and thus freezing the voltage of node T_B; the voltage value of node Over is generated by voltage source B_Ovr, and its output is an IF judgment statement. If the gap voltage is greater than the static breakdown voltage, the output is 1V, otherwise it remains 0V; here, when the IF statement judgment condition is true, the result uses the tanh function to smooth the transition of switch S1 from the off state to the on state to avoid discontinuities that prevent the convergence of the simulation solution; the size of the gap voltage is represented by the voltage at the node V_Gap, which is generated by the behavioral voltage source B_V_Gap, and its output is the absolute value of the voltage difference between nodes T1 and T2; the static breakdown voltage is represented by the voltage at the node V_Break, which is generated by the behavioral voltage source B_V_Brk, and its output uses the following formula, which is applicable to very small gaps under high voltage, and the unit is kV; The breakdown delay time is the time from when the gas discharge switch exceeds the static breakdown voltage to when the switch is closed and the channel is turned on. It is expressed as the voltage at the node delay and is generated by the behavioral voltage source B_Dly. Its output is determined by Martin's empirical formula and the unit is s. Where: E is the gap electric field, in kV / cm, calculated at node E_Gap, generated by the behavioral voltage source B_E_Gap, and its output is the ratio of the node voltage V_Gap to the channel spacing D; ρ is the gap gas volume density, in g / cm3, calculated at node Rho_V, generated by the behavioral voltage source B_Rho, and its output is related to the gap gas pressure and atmospheric pressure; Channel holding current: After the switch S_Ch is initially closed, the gap voltage will drop rapidly and the current will begin to fill the entire loop. In order to maintain the continuity of the closure of the switch S_Ch, it is assumed that there is a minimum current value. When the channel current is greater than the minimum value, there is no need to consider the breakdown delay problem. The switch will continue to be closed and B_Ch_On will maintain the output of 1V. The minimum current value is represented by the node I_Min and is generated by the DC voltage source B_I_Min. When the channel current I_Ch is greater than the minimum value, the V (Maintain) output is 1V. The channel current I_Ch is represented by the voltage at the node I_Ch and is generated by the behavioral current source B_I_Ch, and its output is the absolute value of the channel current.

8. The cold cathode trigger tube circuit simulation SPICE design method as claimed in claim 6, characterized in that: The step (2) comprises: The output of the voltage source B_Res is the product of the current passing through itself and the voltage at the node R_Ch, which represents the channel gap resistance after the gas discharge switch is broken down, in Ω; a formula for calculating the channel resistance based on three parameters: gap distance, channel radius and channel current: Where c is the proportionality constant given by 876, d is the gap distance, i is the channel current, and r is the calculated channel radius in m; Where i is the channel current in kA, t is the channel formation time in μs, and ρ is the gap gas density in g / cm 3 ; The formula is used by the current source B_Ch_Rad to drive the voltage at the node Ch_Rad to represent the channel radius; D4 limits the charging of C5 to the peak output of B_Ch_Rad, and then R3 decays. This combination exists because the derivation of the channel radius calculation formula proposed by Braginskii only considers the pulse-driven channel growth and does not ignore any contraction or dissipation. At the same time, when the channel is not conducting, a switch controlled by the Ch_On node voltage can be used to keep C6 discharged. The Braginskii channel radius expression requires the time after the arc is formed as an input variable. Therefore, a circuit is added to the model to calculate the time of the last transition of the switch S_Ch from off to on. This time is represented by the voltage at the node T_Arc and is generated in the same way as the overvoltage time described above, using the logical inverse of the node Ch_On voltage as the control signal of the sampling and holding circuit, which determines the arc start time at the node T_C.

9. The cold cathode trigger tube circuit simulation SPICE design method as claimed in claim 6, characterized in that: The step (3) specifically includes: In the main circuit, the closed channel inductance is modeled by a behavioral current source B_Ind. After the voltage across the inductor is converted into a current through B_Ind, the current is integrated through capacitor C4, and the result of the integration generates a voltage at the node Int_V_L in units of V∙S×109. Then the current generated by B_Ind is set to the voltage at Int_V_L divided by the voltage at L_Ch to represent the channel inductance in nH. The voltage at the node L_Ch is generated by the voltage source B_L_Ch, and its output uses the inductance expression of an isolated thin line in units of nH. ； Where: d is the gap distance, in cm; r is the channel radius, in m; The output of the voltage source B_L_Ch uses a limiting function limit. This is because when the inductance is too small, the output of the voltage source B_Ind will reach infinity. For a smaller channel radius, an upper limit is set so that the inductance is not too large.

10. The cold cathode trigger tube circuit simulation SPICE design method as claimed in claim 6, characterized in that: The step (4) specifically includes: A trigger voltage with a certain amplitude and a certain width is applied to activate switches S3 and S4. Capacitors C7 and C8 have initial voltages of the same magnitude but opposite directions. When the switches are activated, capacitors C7 and C8 begin to discharge. Lossy transmission line Rg218 is used to simulate the same type of coaxial cable connecting the pulse transmitter and the test unit.

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