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, Available online ,
doi: 10.11884/HPLPB202436.240159
Abstract:
In order to solve the problems of low inhibition of parasitic mode and measurement accuracy that is susceptible to interference of parasitic modes in traditional microwave online measurement devices, a high-power TM01 mode coupling device is studied, which is applied to the Ku-band relativistic backward wave oscillator (RBWO) online measurement system. Due to the RBWO emission angular in homogeneity, the asymmetric mode is generated, and the traditional single-arm porous circular waveguide coupler cannot solve the competition problem between the TM01 mode and other asymmetric modes, which generally leads to the detection waveform distortion and coupling degree judgment deviation and seriously affects the accuracy of the online evaluation of the output power of TM01 mode of RBWO. For this reason, combining the four-arm porous coupling structure with the TM01mode selection network, a novel online mode-selective coupling device is proposed in this paper. Using the field structure difference of different waveguide modes, the proposed device realizes the differential coupling of TM01 mode and other parasitic modes and solves the problem of inaccurate online test power caused by parasitic mode interference.The simulation results show that the coupling degree of the proposed new coupler to TM01 mode is more than 20 dB higher than that of other modes, and the on-line test waveform and power measured in the high-power experiment are in good agreement with the radiated field test waveform and power, and the coupling stability is significantly improved.
In order to solve the problems of low inhibition of parasitic mode and measurement accuracy that is susceptible to interference of parasitic modes in traditional microwave online measurement devices, a high-power TM01 mode coupling device is studied, which is applied to the Ku-band relativistic backward wave oscillator (RBWO) online measurement system. Due to the RBWO emission angular in homogeneity, the asymmetric mode is generated, and the traditional single-arm porous circular waveguide coupler cannot solve the competition problem between the TM01 mode and other asymmetric modes, which generally leads to the detection waveform distortion and coupling degree judgment deviation and seriously affects the accuracy of the online evaluation of the output power of TM01 mode of RBWO. For this reason, combining the four-arm porous coupling structure with the TM01mode selection network, a novel online mode-selective coupling device is proposed in this paper. Using the field structure difference of different waveguide modes, the proposed device realizes the differential coupling of TM01 mode and other parasitic modes and solves the problem of inaccurate online test power caused by parasitic mode interference.The simulation results show that the coupling degree of the proposed new coupler to TM01 mode is more than 20 dB higher than that of other modes, and the on-line test waveform and power measured in the high-power experiment are in good agreement with the radiated field test waveform and power, and the coupling stability is significantly improved.
, Available online ,
doi: 10.11884/HPLPB202537.240228
Abstract:
To assess the susceptibility of road vehicles in complex electromagnetic environments, a radiation immunity testing method of vehicles based on actual electromagnetic environments in reverberation chambers (RCs) is proposed in this paper. We record the actual electromagnetic signals and construct a complex signal playback system in an RC. The cumulative distribution function (CDF) of received power is given. Moreover, this paper provides a field strength calibration method and the radiation immunity testing in an RC. The radiation immunity testing of vehicle is conducted, and the results show that in the complex electromagnetic environment, some vehicles have electromagnetic safety risks in RCs. The proposed method provides important support for enterprises to evaluate the electromagnetic compatibility quality of vehicles.
To assess the susceptibility of road vehicles in complex electromagnetic environments, a radiation immunity testing method of vehicles based on actual electromagnetic environments in reverberation chambers (RCs) is proposed in this paper. We record the actual electromagnetic signals and construct a complex signal playback system in an RC. The cumulative distribution function (CDF) of received power is given. Moreover, this paper provides a field strength calibration method and the radiation immunity testing in an RC. The radiation immunity testing of vehicle is conducted, and the results show that in the complex electromagnetic environment, some vehicles have electromagnetic safety risks in RCs. The proposed method provides important support for enterprises to evaluate the electromagnetic compatibility quality of vehicles.
, Available online ,
doi: 10.11884/HPLPB202436.240254
Abstract:
In order to reduce the threshold of using pulse power source, a compact pulse power source based on Marx generator is designed and implemented. Marx generator is a 7-stage unipolar charging coaxial structure with low inductance ceramic capacitor and ultraviolet preionization output narrow pulse. Use adjustable primary high voltage power supply and 2-way synchronous trigger switch, metal shell as grounding shield and discharge circuit; The generator is filled with high pressure N2. Based on the above design, when the charging voltage is 26 kV and the charging voltage is 0.3 MPa, the high voltage pulse of 33 ns, 59 ns pulse width and 109.2 kV amplitude is obtained on the 60 Ω load. The power source is housed in an aluminum alloy cylinder with a diameter of 0.2 m and a length of 1.1m. This paper provides a design idea and a reference prototype for the realization of compact and modular pulse power source, which can be used as flash X-ray photographic drive source.
In order to reduce the threshold of using pulse power source, a compact pulse power source based on Marx generator is designed and implemented. Marx generator is a 7-stage unipolar charging coaxial structure with low inductance ceramic capacitor and ultraviolet preionization output narrow pulse. Use adjustable primary high voltage power supply and 2-way synchronous trigger switch, metal shell as grounding shield and discharge circuit; The generator is filled with high pressure N2. Based on the above design, when the charging voltage is 26 kV and the charging voltage is 0.3 MPa, the high voltage pulse of 33 ns, 59 ns pulse width and 109.2 kV amplitude is obtained on the 60 Ω load. The power source is housed in an aluminum alloy cylinder with a diameter of 0.2 m and a length of 1.1m. This paper provides a design idea and a reference prototype for the realization of compact and modular pulse power source, which can be used as flash X-ray photographic drive source.
, Available online ,
doi: 10.11884/HPLPB202436.240158
Abstract:
In order to enhance the shock wave generated by underwater electrical wire explosion(UEWE), wires are connected in parallel to form wire-array, but wire-array’s low resistance result in low deposition power. To solve the problem, by using copper sheets, parallel-series wire-arrays with different resistance and same mass were designed, and it was proposed that resistance matching between wire-array and power source is the ideal discharge mode. By parallel-series wire-array, single wire discharge similarity was verified, and miniaturization verification of large devices with high voltage was achieved. With the help of discharge similarity and parallel-series wire-array, the optimal wire-array design of UEWE was proposed at a given energy and wire mass.
In order to enhance the shock wave generated by underwater electrical wire explosion(UEWE), wires are connected in parallel to form wire-array, but wire-array’s low resistance result in low deposition power. To solve the problem, by using copper sheets, parallel-series wire-arrays with different resistance and same mass were designed, and it was proposed that resistance matching between wire-array and power source is the ideal discharge mode. By parallel-series wire-array, single wire discharge similarity was verified, and miniaturization verification of large devices with high voltage was achieved. With the help of discharge similarity and parallel-series wire-array, the optimal wire-array design of UEWE was proposed at a given energy and wire mass.
Articles in press have been peer-reviewed and accepted, which are not yet assigned to volumes /issues, but are citable by Digital Object Identifier (DOI).
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2024, 36: 115001.
doi: 10.11884/HPLPB202436.240332
Abstract:
For vacuum switches used in space environments, it is possible to eliminate the sealing structures and ancillary vacuum pumping equipment required in artificial environments, effectively reducing the volume and weight. They have the inherent advantages of a vacuum environment, no need for sealing, high insulation strength, and fast recovery speed, making them highly potential for application in space environments. Firstly, it is systemically introduced the research advances of vacuum switches domestic and overseas. And it is analyzed and compared the operating characteristics of various types of vacuum switches. Especially, the emphasis is put on the summary of the conduction mechanism of self-breakdown flashover vacuum switch and trigger vacuum switch. Secondly, it is analyzed the application research of cold cathode materials. Thirdly, it is summarized the research advances on cold cathode vacuum switch in National University of Defense Technology. Finally, it is discussed the development trend of the cold cathode vacuum switch. Research results lay a solid technical foundation for the application of pulse power driving source in space environment.
For vacuum switches used in space environments, it is possible to eliminate the sealing structures and ancillary vacuum pumping equipment required in artificial environments, effectively reducing the volume and weight. They have the inherent advantages of a vacuum environment, no need for sealing, high insulation strength, and fast recovery speed, making them highly potential for application in space environments. Firstly, it is systemically introduced the research advances of vacuum switches domestic and overseas. And it is analyzed and compared the operating characteristics of various types of vacuum switches. Especially, the emphasis is put on the summary of the conduction mechanism of self-breakdown flashover vacuum switch and trigger vacuum switch. Secondly, it is analyzed the application research of cold cathode materials. Thirdly, it is summarized the research advances on cold cathode vacuum switch in National University of Defense Technology. Finally, it is discussed the development trend of the cold cathode vacuum switch. Research results lay a solid technical foundation for the application of pulse power driving source in space environment.
2024, 36: 115002.
doi: 10.11884/HPLPB202436.240345
Abstract:
Electromagnetic pulse welding (EMPW) is a key application of pulsed power technology in materials processing, where triggered vacuum switch (TVS) is frequently employed as discharge switch. Based on the specific behavior of the EMPW process, this paper presents a detailed investigation into the operational characteristics of a new domestically produced TVS, named ZKTC. The study focuses on the switch's behavior during the triggering, conducting, and initial discharging stages. The effects of circuit parameters on ZKTC's operation were analyzed through simulations. A trigger device combining a Marx circuit and a pulse transformer was developed, featuring adjustable pulse widths (0–10 μs) and adjustable voltage amplitudes (0–20 kV). Based on ZKTC, a high-current pulsed generator testing platform with a discharge energy of 27 kJ was constructed to perform experimental analyses. The results indicate that the voltage amplitude and rising edge of the trigger signal significantly influence the ZKTC triggering process. While the working voltage amplitude of the main discharge circuit impacts the directional migration rate of charged particles and the discharge current during the conducting stage, modifying the parameters of the switch discharge circuit and accelerating the voltage drop rate. This, in turn, has a significant effect on both the conducting and discharging stages.
Electromagnetic pulse welding (EMPW) is a key application of pulsed power technology in materials processing, where triggered vacuum switch (TVS) is frequently employed as discharge switch. Based on the specific behavior of the EMPW process, this paper presents a detailed investigation into the operational characteristics of a new domestically produced TVS, named ZKTC. The study focuses on the switch's behavior during the triggering, conducting, and initial discharging stages. The effects of circuit parameters on ZKTC's operation were analyzed through simulations. A trigger device combining a Marx circuit and a pulse transformer was developed, featuring adjustable pulse widths (0–10 μs) and adjustable voltage amplitudes (0–20 kV). Based on ZKTC, a high-current pulsed generator testing platform with a discharge energy of 27 kJ was constructed to perform experimental analyses. The results indicate that the voltage amplitude and rising edge of the trigger signal significantly influence the ZKTC triggering process. While the working voltage amplitude of the main discharge circuit impacts the directional migration rate of charged particles and the discharge current during the conducting stage, modifying the parameters of the switch discharge circuit and accelerating the voltage drop rate. This, in turn, has a significant effect on both the conducting and discharging stages.
2024, 36: 115003.
doi: 10.11884/HPLPB202436.240325
Abstract:
Electrically triggered vacuum surface flashover switch (VSFS) has the advantages of high conduction speed, high insulation recovery speed, small size and simple structure, which make them suitable for high voltage and high power conversion. Conduction speed and stability are important indicators of VSFS output performance, and the study of their influencing factors determines the optimization direction of VSFS. In this paper, the effects of structure, material, and trigger polarity on the output performance of vacuum surface flashover switch are investigated. The results show that the bulk structure has faster and more stable conduction speed compared with the chip structure. Barium titanate dielectric and aluminum nitride dielectric have stable pulse breakdown voltage and are suitable as trigger dielectric. Quartz has a high DC withstand voltage and is suitable for the main gap medium. The output index of the switch in positive triggering mode is better than in negative triggering.
Electrically triggered vacuum surface flashover switch (VSFS) has the advantages of high conduction speed, high insulation recovery speed, small size and simple structure, which make them suitable for high voltage and high power conversion. Conduction speed and stability are important indicators of VSFS output performance, and the study of their influencing factors determines the optimization direction of VSFS. In this paper, the effects of structure, material, and trigger polarity on the output performance of vacuum surface flashover switch are investigated. The results show that the bulk structure has faster and more stable conduction speed compared with the chip structure. Barium titanate dielectric and aluminum nitride dielectric have stable pulse breakdown voltage and are suitable as trigger dielectric. Quartz has a high DC withstand voltage and is suitable for the main gap medium. The output index of the switch in positive triggering mode is better than in negative triggering.
2024, 36: 115004.
doi: 10.11884/HPLPB202436.240331
Abstract:
Solid state pulse power sources are widely used in the field of pulse power technology and have become a new research hotspot. Among them, high-power solid-state switching devices are the core of solid-state pulse power sources. This article reports a new type of laser initiated multi gate semiconductor switch (LIMS), which has two working modes: photo induced linear mode and field induced gain mode. It solves the problem of low current rise rate in traditional electronic control devices and achieves high current rise rate of the device. Experimental tests in photo induced linear mode showed a current rise rate of 454 kA/μs. The switch has been preliminarily applied in fields such as detonator initiation and electromagnetic pulse simulation.
Solid state pulse power sources are widely used in the field of pulse power technology and have become a new research hotspot. Among them, high-power solid-state switching devices are the core of solid-state pulse power sources. This article reports a new type of laser initiated multi gate semiconductor switch (LIMS), which has two working modes: photo induced linear mode and field induced gain mode. It solves the problem of low current rise rate in traditional electronic control devices and achieves high current rise rate of the device. Experimental tests in photo induced linear mode showed a current rise rate of 454 kA/μs. The switch has been preliminarily applied in fields such as detonator initiation and electromagnetic pulse simulation.
2024, 36: 115005.
doi: 10.11884/HPLPB202436.240321
Abstract:
The beam spot is one of the important factors affecting the on-state performance of photoconductive switches. The on-state performance of the GaN photoconductive switch has been tested under the triggering of Gaussian beam and flat-top beam. As the energy uniformity of flat-top beam is better than that of Gaussian beam, the results show that the voltage conversion efficiency is increased by 6.8% under the same applied bias voltage (800 V), Triggered by flat-top beam at a laser energy of 500 μJ, GaN PCSS shows a maximum peak output voltage of4550 V, at the same time the output power reaches 414 kW and the conduction is 13.7 Ω. The output waveform has a rise time of 420 ps and a fall time of 5 ns.
The beam spot is one of the important factors affecting the on-state performance of photoconductive switches. The on-state performance of the GaN photoconductive switch has been tested under the triggering of Gaussian beam and flat-top beam. As the energy uniformity of flat-top beam is better than that of Gaussian beam, the results show that the voltage conversion efficiency is increased by 6.8% under the same applied bias voltage (800 V), Triggered by flat-top beam at a laser energy of 500 μJ, GaN PCSS shows a maximum peak output voltage of
2024, 36: 115006.
doi: 10.11884/HPLPB202436.240161
Abstract:
Avalanche gallium arsenide photoconductive semiconductor switches (GaAs PCSSs ) have a wide range of applications due to their ultra-fast switching speed, low triggering jitter , optoelectronic isolation , high power capacity, high repetition frequency, and flexible device structure. In this paper, GaAs PCSSs with an anisotropic structure and an electrode gap of 5 mm are fabricated and packaged. The electrical characteristics of the switch in dark-state and on-states under different bias electric fields (36−76 kV/cm) are analyzed, featuring a rising edge in the order of hundred picosecond to nanosecond, low dark-state leakage current (0.15−6.61 μA) and high withstand voltage (18−38 kV). The relationship between the number of switching operations and the peak output voltage is explored. The experimental results show that the output voltage amplitude tends to decrease in a stepwise manner with the increase of the number of operations. The switch lifetime reaches 4.0 × 104 times at 20 kV and 2 Hz.
Avalanche gallium arsenide photoconductive semiconductor switches (GaAs PCSSs ) have a wide range of applications due to their ultra-fast switching speed, low triggering jitter , optoelectronic isolation , high power capacity, high repetition frequency, and flexible device structure. In this paper, GaAs PCSSs with an anisotropic structure and an electrode gap of 5 mm are fabricated and packaged. The electrical characteristics of the switch in dark-state and on-states under different bias electric fields (36−76 kV/cm) are analyzed, featuring a rising edge in the order of hundred picosecond to nanosecond, low dark-state leakage current (0.15−6.61 μA) and high withstand voltage (18−38 kV). The relationship between the number of switching operations and the peak output voltage is explored. The experimental results show that the output voltage amplitude tends to decrease in a stepwise manner with the increase of the number of operations. The switch lifetime reaches 4.0 × 104 times at 20 kV and 2 Hz.
2024, 36: 115007.
doi: 10.11884/HPLPB202436.240238
Abstract:
In this paper, a bipolar solid-state pulsed power source based on gallium arsenide (GaAs) photoconductive semiconductor switch (PCSS) is designed. By studying the reflection coefficients at the structural end of the two-stage pulse forming line (PFL), the wave processes of single-stage positive and negative pulses as well as bipolar pulses are analysed, and the circuit simulation is carried out by using the PSpice tool. The effect of resistive impedance at the input end on pulse trailing is investigated, and the methods of pulse trailing modulation and pulse width modulation are proposed. Based on the vertically structured GaAs PCSS and the two-stage pulse-forming line structure, a resistor-isolated pulse charging experimental platform is constructed, and the optical path time-triggering technique is adopted to regulate the on-time sequence of the photoconductive switch. The experimental results show that the developed bipolar solid-state pulsed power source generator can produce bipolar nanosecond impulse with peak-to-peak values up to 3.26 kV, pulse widths of 5.6 ns, and a repetition frequency of 1 kHz under a bias voltage of 2.5 kV, which verifies the feasibility of generating bipolar nanosecond impulse by combining an avalanche GaAs PCSS with a multilevel wave topology PFL.
In this paper, a bipolar solid-state pulsed power source based on gallium arsenide (GaAs) photoconductive semiconductor switch (PCSS) is designed. By studying the reflection coefficients at the structural end of the two-stage pulse forming line (PFL), the wave processes of single-stage positive and negative pulses as well as bipolar pulses are analysed, and the circuit simulation is carried out by using the PSpice tool. The effect of resistive impedance at the input end on pulse trailing is investigated, and the methods of pulse trailing modulation and pulse width modulation are proposed. Based on the vertically structured GaAs PCSS and the two-stage pulse-forming line structure, a resistor-isolated pulse charging experimental platform is constructed, and the optical path time-triggering technique is adopted to regulate the on-time sequence of the photoconductive switch. The experimental results show that the developed bipolar solid-state pulsed power source generator can produce bipolar nanosecond impulse with peak-to-peak values up to 3.26 kV, pulse widths of 5.6 ns, and a repetition frequency of 1 kHz under a bias voltage of 2.5 kV, which verifies the feasibility of generating bipolar nanosecond impulse by combining an avalanche GaAs PCSS with a multilevel wave topology PFL.
2024, 36: 115008.
doi: 10.11884/HPLPB202436.240213
Abstract:
Because of its high repetition rate and reliability, solid-state pulsed power generator is an important aspect of pulsed power technology. The solid-state switches play a critical role in this technology, and among them the magnetic switch stands out due to its long lifespan, high power capacity and free of maintenance. This manuscript delves into the key technologies and typical applications of magnetic switches. Furthermore, utilizing a field-circuit co-simulation model of magnetic switches, the manuscript analyzes the working characteristics of magnetic cores. The model includes processes like magnetic core saturation, interlamination electric field strength, and energy loss across various time scales. Additionally, the manuscript explores the influence of magnetic core geometry. Finally, it presents applications utilizing magnetic switch technology, such as compact solid-state high-power pulse generators and magnetic synchronization technology.
Because of its high repetition rate and reliability, solid-state pulsed power generator is an important aspect of pulsed power technology. The solid-state switches play a critical role in this technology, and among them the magnetic switch stands out due to its long lifespan, high power capacity and free of maintenance. This manuscript delves into the key technologies and typical applications of magnetic switches. Furthermore, utilizing a field-circuit co-simulation model of magnetic switches, the manuscript analyzes the working characteristics of magnetic cores. The model includes processes like magnetic core saturation, interlamination electric field strength, and energy loss across various time scales. Additionally, the manuscript explores the influence of magnetic core geometry. Finally, it presents applications utilizing magnetic switch technology, such as compact solid-state high-power pulse generators and magnetic synchronization technology.
2024, 36: 115009.
doi: 10.11884/HPLPB202436.240329
Abstract:
This paper introducesd the composition and working principle of the integrated magnetic switch based on fractional-turn ratio saturable pulse transformer. The integrated magnetic switch can realize the functions of solid-state magnetic switch, pulse modulation and voltage boost. Three typical applications of the integrated magnetic switch are also provided. First, it can be applied in high-voltage pulse trigger, which can realize the voltage greater than 100 kV, and jitter less than 5 ns at 30 Hz; Second, it is used for microsecond quasi-square pulse generation, producing larger than 50 kV and microsecond-range pulses continuously at 100 Hz; Third, as the main switch of the low-resistance pulse forming line, to output square pulses of 100 ns with dual-switch modulation technique to realize the lightweight of the pulse power device. The integrated magnetic switch based on fractional-turn ratio saturable pulse transformer is a compact pulse power device, which can take into account the high boost ratio of transformer and the low secondary saturation inductance of magnetic switch. It is of great significance for the realization of solid state and compactness of pulse power device.
This paper introducesd the composition and working principle of the integrated magnetic switch based on fractional-turn ratio saturable pulse transformer. The integrated magnetic switch can realize the functions of solid-state magnetic switch, pulse modulation and voltage boost. Three typical applications of the integrated magnetic switch are also provided. First, it can be applied in high-voltage pulse trigger, which can realize the voltage greater than 100 kV, and jitter less than 5 ns at 30 Hz; Second, it is used for microsecond quasi-square pulse generation, producing larger than 50 kV and microsecond-range pulses continuously at 100 Hz; Third, as the main switch of the low-resistance pulse forming line, to output square pulses of 100 ns with dual-switch modulation technique to realize the lightweight of the pulse power device. The integrated magnetic switch based on fractional-turn ratio saturable pulse transformer is a compact pulse power device, which can take into account the high boost ratio of transformer and the low secondary saturation inductance of magnetic switch. It is of great significance for the realization of solid state and compactness of pulse power device.
2024, 36: 115010.
doi: 10.11884/HPLPB202436.240313
Abstract:
This paper introduces a pseudo-spark switch which works in positive and negative polarity and does not need hot wire power supply. It can be triggered by one of the three modes of electric triggering, space light and fiber transmission laser energy. In the electric trigger mode, the technical specifications of the switch reach the operating voltage ±60 kV, the pulse current16.2 kA and the close jitter 7 ns; In space light trigger mode, the close jitter is 3 ns using 1 mJ/532 nm laser, and the minimum triggering laser energy is 0.15 mJ. In the fiber transmission laser energy mode (the energy of the incident end of the fiber is 7 mJ/the output end is 5 mJ), the close jitter is 3 ns.
This paper introduces a pseudo-spark switch which works in positive and negative polarity and does not need hot wire power supply. It can be triggered by one of the three modes of electric triggering, space light and fiber transmission laser energy. In the electric trigger mode, the technical specifications of the switch reach the operating voltage ±60 kV, the pulse current16.2 kA and the close jitter 7 ns; In space light trigger mode, the close jitter is 3 ns using 1 mJ/532 nm laser, and the minimum triggering laser energy is 0.15 mJ. In the fiber transmission laser energy mode (the energy of the incident end of the fiber is 7 mJ/the output end is 5 mJ), the close jitter is 3 ns.
2024, 36: 115011.
doi: 10.11884/HPLPB202436.240086
Abstract:
Currently, the research on pseudospark switches triggered by laser mainly focuses on triggering by ultraviolet laser, and the physical triggering mechanism is generally considered to be photoemission. However, when the weakly focused ultraviolet laser irradiates the photoelectric material (target) in a low electric field environment, the seed electrons generated by the photoemission are very limited. To further reveal the physical mechanism of the switches triggered by the weakly focused ultraviolet laser, we established the test experimental platform for discharge of pseudospark switches triggered by weakly focused 266 nm ultraviolet laser. On this basis, the emission characteristics of seed electrons irradiated by laser were tested. The effects of laser energy, switch voltage, gas pressure, target material and irradiation position on the trigger characteristics of the switch were studied, and the source of seed electrons and their contribution to trigger were analyzed. The results show that when the laser is irradiated on the edge of the hole on the back of the cathode, the prompt electrons generated by the photoemission are not the main source of the seed electrons, and the ultrafast electrons related to the ablation plasma are the main source. Therefore, when the laser is irradiated on the edge of the hole on the back of the cathode, the material with low density and melting boiling point is more suitable as the target material for pseudospark switch triggered by weakly focused ultraviolet laser. According to the testing result, in this case, the operating voltage is −15 kV, and the pressure is 80 Pa (helium), the minimum laser energy of the switch with magnesium as the target can achieve stable trigger conduction is 2 mJ, which is much lower than that of copper (6 mJ) and molybdenum (8 mJ). In addition, under the same conditions, when the laser is irradiated on the inner wall of the cathode hole of the switch, the trigger delay and jitter are 36.9 ns and 1.41 ns, which are much lower than those when the laser is irradiated on the edge of the hole on the back of the cathode (116.4 ns and 5.39 ns).
Currently, the research on pseudospark switches triggered by laser mainly focuses on triggering by ultraviolet laser, and the physical triggering mechanism is generally considered to be photoemission. However, when the weakly focused ultraviolet laser irradiates the photoelectric material (target) in a low electric field environment, the seed electrons generated by the photoemission are very limited. To further reveal the physical mechanism of the switches triggered by the weakly focused ultraviolet laser, we established the test experimental platform for discharge of pseudospark switches triggered by weakly focused 266 nm ultraviolet laser. On this basis, the emission characteristics of seed electrons irradiated by laser were tested. The effects of laser energy, switch voltage, gas pressure, target material and irradiation position on the trigger characteristics of the switch were studied, and the source of seed electrons and their contribution to trigger were analyzed. The results show that when the laser is irradiated on the edge of the hole on the back of the cathode, the prompt electrons generated by the photoemission are not the main source of the seed electrons, and the ultrafast electrons related to the ablation plasma are the main source. Therefore, when the laser is irradiated on the edge of the hole on the back of the cathode, the material with low density and melting boiling point is more suitable as the target material for pseudospark switch triggered by weakly focused ultraviolet laser. According to the testing result, in this case, the operating voltage is −15 kV, and the pressure is 80 Pa (helium), the minimum laser energy of the switch with magnesium as the target can achieve stable trigger conduction is 2 mJ, which is much lower than that of copper (6 mJ) and molybdenum (8 mJ). In addition, under the same conditions, when the laser is irradiated on the inner wall of the cathode hole of the switch, the trigger delay and jitter are 36.9 ns and 1.41 ns, which are much lower than those when the laser is irradiated on the edge of the hole on the back of the cathode (116.4 ns and 5.39 ns).
2024, 36: 115012.
doi: 10.11884/HPLPB202436.240149
Abstract:
A set of nanosecond pulsed power supply was set up with a field distortion spark switch under atmospheric air, and the voltage operating range of the switch triggered to breakdown at different repetition frequencies (from 50 Hz to1300 Hz) as well as the effect of blowing were investigated. The voltage waveforms were recorded with a high voltage probe and a digital oscilloscope. Experimental results show that when the switch operates stably (voltage below 30 kV and current below 300 A), the highest repetition frequency is 1300 Hz. Due to incomplete recovery of gas insulation after the switch breaks down, both the maximum operating voltage \begin{document}$ {V}_{\mathrm{m}\mathrm{a}\mathrm{x}} $\end{document} ![]()
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1300 Hz, only about 0.5 kV. This is because the insulation level is low at high frequency, and the trigger pulse has little effect on breakdown, so the actual operating voltage under trigger condition is closer to the current self-breakdown voltage. Blowing can accelerate gas insulation recovery and increase the maximum and minimum operating voltage. If the maximum operating voltage is higher than 90% of the self-breakdown voltage of 30 kV before operation, the repetition frequency is lower than 50 Hz without blowing and goes up to 500 Hz with blowing.
A set of nanosecond pulsed power supply was set up with a field distortion spark switch under atmospheric air, and the voltage operating range of the switch triggered to breakdown at different repetition frequencies (from 50 Hz to
2024, 36: 115013.
doi: 10.11884/HPLPB202436.240324
Abstract:
The lifetime test of initial designed nylon packaged coaxial three-electrode gas spark switch has finished. It shows that the lifetimes of three switch samples are 204 000, 433 000 and 151 000 times, respectively. Based on the test results, an improved design with respect to structure and insulator material of switch is proposed. Preliminary test results show that each of the three switch samples with PMMA insulator has finished 300 000 shots, and their self-breakdown voltages keep good stability. According to variation of self-breakdown voltage, the delay time and jitter of switches in triggering experiments, the predicted lifetime of the switch of the improved design will exceed that of the initial former design.
The lifetime test of initial designed nylon packaged coaxial three-electrode gas spark switch has finished. It shows that the lifetimes of three switch samples are 204 000, 433 000 and 151 000 times, respectively. Based on the test results, an improved design with respect to structure and insulator material of switch is proposed. Preliminary test results show that each of the three switch samples with PMMA insulator has finished 300 000 shots, and their self-breakdown voltages keep good stability. According to variation of self-breakdown voltage, the delay time and jitter of switches in triggering experiments, the predicted lifetime of the switch of the improved design will exceed that of the initial former design.
2024, 36: 115014.
doi: 10.11884/HPLPB202436.240141
Abstract:
Gas switches with high power capacity are the first choice for large-scale pulsed power devices at home and abroad, but the self-breakdown voltage jitter due to the randomness of gas discharge has always been the bottleneck problem for pulsed power devices. The electrode is the key to affect the stability and life of the gas switch, and the previous designs had to face the trade-off between low jitter and long life. This paper proposes a spherical graphite cast iron gas switch that takes into account the characteristics of low jitter and long life. Based on the characterization of the spherical graphite cast iron material, it is proposed that the uniform distribution of spherical graphite in the electrode is conducive to the mechanism of improving the breakdown stability of the gas switch, and the spherical graphite is uniformly distributed in the whole electrode, which has the native advantage of long life compared with the surface structure. A single-stage switching stability test experiment was designed and carried out, and the results show that the ductile graphite electrode can effectively reduce the heavy frequency self-breakdown jitter of 3%−4% in the traditional electrode structure to 2.5%. Ultimately, a 5-stage 1 MV equal self-breakdown probability type fully sealed gas switch was designed using low jitter ductile electrodes, and the switching jitter was further reduced to less than 2%. Under the test voltage range of 960-980 kV, discharge current of about 9 kA, and maintenance-free conditions, the switch was tested for 300 000 pulses, and the self-breakdown jitter was maintained at less than 2%, with an optimum of 1.7%. The switch conduction front is less than 5 ns, and the transmission efficiency is more than 90%. The results demonstrate the potential application of spherical graphite cast iron cathodes as gas switches.
Gas switches with high power capacity are the first choice for large-scale pulsed power devices at home and abroad, but the self-breakdown voltage jitter due to the randomness of gas discharge has always been the bottleneck problem for pulsed power devices. The electrode is the key to affect the stability and life of the gas switch, and the previous designs had to face the trade-off between low jitter and long life. This paper proposes a spherical graphite cast iron gas switch that takes into account the characteristics of low jitter and long life. Based on the characterization of the spherical graphite cast iron material, it is proposed that the uniform distribution of spherical graphite in the electrode is conducive to the mechanism of improving the breakdown stability of the gas switch, and the spherical graphite is uniformly distributed in the whole electrode, which has the native advantage of long life compared with the surface structure. A single-stage switching stability test experiment was designed and carried out, and the results show that the ductile graphite electrode can effectively reduce the heavy frequency self-breakdown jitter of 3%−4% in the traditional electrode structure to 2.5%. Ultimately, a 5-stage 1 MV equal self-breakdown probability type fully sealed gas switch was designed using low jitter ductile electrodes, and the switching jitter was further reduced to less than 2%. Under the test voltage range of 960-980 kV, discharge current of about 9 kA, and maintenance-free conditions, the switch was tested for 300 000 pulses, and the self-breakdown jitter was maintained at less than 2%, with an optimum of 1.7%. The switch conduction front is less than 5 ns, and the transmission efficiency is more than 90%. The results demonstrate the potential application of spherical graphite cast iron cathodes as gas switches.
2024, 36: 115015.
doi: 10.11884/HPLPB202436.240291
Abstract:
The primary discharge circuit composed of switch and capacitors is the basic unit of fast linear transformer driver (FLTD). Under the condition that the amplitude and rise time of the output current are constant, the number of the units and the gas switches can be reduced effectively by reducing the inductance of the unit circuit, thus the overall reliability of FLTD can be improved. Therefore, reducing the inductance of the primary discharge circuit is always the key technology of FLTD. A low inductance FLTD primary discharge unit is developed based on switch and capacitor assembly technology in this paper. The unit uses ring-shaped high voltage pulse capacitor as energy storage element. Its operating voltage is 100 kV, capacity is 39.6 nF, and internal inductance is 8.8 nH. The working characteristics of the primary discharge unit are tested. The experimental results show that when the charging voltage of the capacitor is ±50 kV, the short-circuit output current amplitude of the primary discharge unit is 40 kA, the rise time is 50 ns, and the loop inductance is 101 nH. When the charging voltage of the capacitor is ±80 kV, the output current amplitude of the primary discharge unit to the matched load is 30 kA and the rise time is 66 ns.
The primary discharge circuit composed of switch and capacitors is the basic unit of fast linear transformer driver (FLTD). Under the condition that the amplitude and rise time of the output current are constant, the number of the units and the gas switches can be reduced effectively by reducing the inductance of the unit circuit, thus the overall reliability of FLTD can be improved. Therefore, reducing the inductance of the primary discharge circuit is always the key technology of FLTD. A low inductance FLTD primary discharge unit is developed based on switch and capacitor assembly technology in this paper. The unit uses ring-shaped high voltage pulse capacitor as energy storage element. Its operating voltage is 100 kV, capacity is 39.6 nF, and internal inductance is 8.8 nH. The working characteristics of the primary discharge unit are tested. The experimental results show that when the charging voltage of the capacitor is ±50 kV, the short-circuit output current amplitude of the primary discharge unit is 40 kA, the rise time is 50 ns, and the loop inductance is 101 nH. When the charging voltage of the capacitor is ±80 kV, the output current amplitude of the primary discharge unit to the matched load is 30 kA and the rise time is 66 ns.
2024, 36: 115016.
doi: 10.11884/HPLPB202436.240005
Abstract:
The pre-fire of gas switches is the unexpected breakdown at triggered mode, which is the main factor restricting the development and engineering application of linear transformer driver (LTD). In this paper, the dispersion of breakdown voltage as well as pre-fire rate of multi-gap gas switches under typical working pressures of LTD was investigated and reported. A simplified gas switch was designed to measure self-breakdown voltage at higher gas pressures, and the cumulative distribution function of self-breakdown voltage considering uneven gap voltage distribution was derived. The self-breakdown voltage distribution characteristics of multi-gap switches under LTD working pressure were calculated and experimentally verified. The estimated pre-fire rate was obtained by using peak-over-threshold method to fit the Weibull distribution of small probability pre-fire events under low working coefficients. The measured pre-fire rate was obtained by a 10 000 triggering test. The results show that the dispersion of the self-breakdown voltage of the switch increased with air pressure. Measuring the self-breakdown voltage at low air pressure can not extrapolate the pre-fire rate at high pressure under actual working conditions. When the working coefficients of the gas switch were 65% and 60%, the estimated pre-fire rates were\begin{document}$1.44 \times {10^{ - 4}}$\end{document} ![]()
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The pre-fire of gas switches is the unexpected breakdown at triggered mode, which is the main factor restricting the development and engineering application of linear transformer driver (LTD). In this paper, the dispersion of breakdown voltage as well as pre-fire rate of multi-gap gas switches under typical working pressures of LTD was investigated and reported. A simplified gas switch was designed to measure self-breakdown voltage at higher gas pressures, and the cumulative distribution function of self-breakdown voltage considering uneven gap voltage distribution was derived. The self-breakdown voltage distribution characteristics of multi-gap switches under LTD working pressure were calculated and experimentally verified. The estimated pre-fire rate was obtained by using peak-over-threshold method to fit the Weibull distribution of small probability pre-fire events under low working coefficients. The measured pre-fire rate was obtained by a 10 000 triggering test. The results show that the dispersion of the self-breakdown voltage of the switch increased with air pressure. Measuring the self-breakdown voltage at low air pressure can not extrapolate the pre-fire rate at high pressure under actual working conditions. When the working coefficients of the gas switch were 65% and 60%, the estimated pre-fire rates were
2024, 36: 115017.
doi: 10.11884/HPLPB202436.240206
Abstract:
The 12-stage linear transformer driver (LTD) adopts the novel method of internal in situ triggering in sequence, and puts forward the technical requirements of low pre-fire probability, low trigger threshold voltage, low jitter and adjustable trigger delay time for the trigger brick gas switches. This paper introduces the structure and working principle of the trigger brick gas switch based on resistance voltage balance and corona assisted triggering technology. The test platform of gas switch characteristics is established, and after the process of conditioning, the breakdown characteristics of 12 gas switches are tested. Then, the switches are applied to the 12-stage LTD to carry out cascade triggering experiments, and the triggering characteristic parameters under different charging voltages and working coefficients are obtained. The experimental results show that, when the charging voltage of the switch is ±60−±80 kV and the working coefficient is 60%−80%, the jitter is lower than 2 ns, and there is no pre-fire in more than 500 shots. The trigger brick gas switches of the 12-stage LTD can be sequentially closed according to the ideal sequence, and the trigger sequence coefficient can be adjusted in the range of 0.83−1.17.
The 12-stage linear transformer driver (LTD) adopts the novel method of internal in situ triggering in sequence, and puts forward the technical requirements of low pre-fire probability, low trigger threshold voltage, low jitter and adjustable trigger delay time for the trigger brick gas switches. This paper introduces the structure and working principle of the trigger brick gas switch based on resistance voltage balance and corona assisted triggering technology. The test platform of gas switch characteristics is established, and after the process of conditioning, the breakdown characteristics of 12 gas switches are tested. Then, the switches are applied to the 12-stage LTD to carry out cascade triggering experiments, and the triggering characteristic parameters under different charging voltages and working coefficients are obtained. The experimental results show that, when the charging voltage of the switch is ±60−±80 kV and the working coefficient is 60%−80%, the jitter is lower than 2 ns, and there is no pre-fire in more than 500 shots. The trigger brick gas switches of the 12-stage LTD can be sequentially closed according to the ideal sequence, and the trigger sequence coefficient can be adjusted in the range of 0.83−1.17.
2024, 36: 115018.
doi: 10.11884/HPLPB202436.240305
Abstract:
To achieve precise control of the main triggered switch of the pulsed power source, a triggered gas switch based on the principle of corona stabilization was developed. The process of stabilized corona discharge and the influence of high-energy runaway electrons on the stability of breakdown were analyzed. This study also revealed the mechanism by which suppressing high-energy runaway electrons was beneficial in increasing the stability of gas switch self-breakdown. The experimental study was carried out from the perspectives of gas medium and E-field conditions, and the self-breakdown stability of the gas switch was compared. The self-breakdown dispersion of the gas switch filled with 15% SF6/N2 mixed gas was no more than 6% within the pressure of 0.06 MPa to 0.56 MPa, while the lowest value was 1.4%. The self-breakdown voltage dispersion remained within the range of 2%-4% when the electrically negative gas content in the SF6/N2 mixed gas was less than 30%. Within the charging voltage range of less than1800 V, by changing the time-domain variation speed of the E-field in the gap, the self-breakdown voltage dispersion could be reduced to 0.2% with the breakdown voltage of 242 kV, while the voltage on the high voltage electrode rising speed was 12.4 kV/μs. However, reducing the field non-uniform coefficient didn`t significantly improve the breakdown stability in the 15% SF6/N2 mixed gas at 0.3 MPa, but the self-breakdown voltage dispersion was still kept below 1% when the voltage rising speed increased on the high voltage electrode. By replacing the wedge-shaped trigger electrode with a groove-shaped trigger electrode, the minimum self-breakdown voltage dispersion could be as low as 0.15%, and the breakdown voltage was stabilized around 248 kV.
To achieve precise control of the main triggered switch of the pulsed power source, a triggered gas switch based on the principle of corona stabilization was developed. The process of stabilized corona discharge and the influence of high-energy runaway electrons on the stability of breakdown were analyzed. This study also revealed the mechanism by which suppressing high-energy runaway electrons was beneficial in increasing the stability of gas switch self-breakdown. The experimental study was carried out from the perspectives of gas medium and E-field conditions, and the self-breakdown stability of the gas switch was compared. The self-breakdown dispersion of the gas switch filled with 15% SF6/N2 mixed gas was no more than 6% within the pressure of 0.06 MPa to 0.56 MPa, while the lowest value was 1.4%. The self-breakdown voltage dispersion remained within the range of 2%-4% when the electrically negative gas content in the SF6/N2 mixed gas was less than 30%. Within the charging voltage range of less than
2024, 36: 115019.
doi: 10.11884/HPLPB202436.240311
Abstract:
A study was conducted on the spark channel resistance and thermal effect characteristics of a two-electrode spark gap switch applied to a high-power repetition-rate Marx-type pulse power source. The influencing factors of the thermal effect of the spark gap channel resistance were analyzed, and the temperature and pressure changes inside the switch chamber under continuous repetition-rate working conditions were studied. The research results indicate that the pressure and temperature inside the switch chamber show a trend of rapid increase followed by slow increase and stabilization with the increase of working time. The increase of pulse current has a significant effect on the increase of heat deposition. Based on the two-electrode spark gap switch used in this article, 9 000 pulses were continuously operated under the conditions of peak conduction current of 14.7 kA and pulse width of 160 ns. The discharge channel of the switch generated about 36.6 kJ of heat. During the current conduction time, the average resistance of the spark channel was calculated to be about 0.12 Ω through Joule heating effect.
A study was conducted on the spark channel resistance and thermal effect characteristics of a two-electrode spark gap switch applied to a high-power repetition-rate Marx-type pulse power source. The influencing factors of the thermal effect of the spark gap channel resistance were analyzed, and the temperature and pressure changes inside the switch chamber under continuous repetition-rate working conditions were studied. The research results indicate that the pressure and temperature inside the switch chamber show a trend of rapid increase followed by slow increase and stabilization with the increase of working time. The increase of pulse current has a significant effect on the increase of heat deposition. Based on the two-electrode spark gap switch used in this article, 9 000 pulses were continuously operated under the conditions of peak conduction current of 14.7 kA and pulse width of 160 ns. The discharge channel of the switch generated about 36.6 kJ of heat. During the current conduction time, the average resistance of the spark channel was calculated to be about 0.12 Ω through Joule heating effect.
2024, 36: 115020.
doi: 10.11884/HPLPB202436.240328
Abstract:
The superconducting tokamak device constrains high-temperature plasma through an extremely high magnetic field to achieve a controllable nuclear fusion reaction. To ensure the safe operation of the superconducting magnets, the quench protection system relies on pyrobreaker for critical backup protection. In this paper, the numerical model of current contacts in the 15 kV pyrobreaker has been established and the analysis is carried out for the contact breaking process. The detonation pressure required for contact separation and the pressure distribution law generated by the explosion are calculated. Furthermore, the accuracy of the numerical simulations is verified through experimental validation, providing a theoretical foundation for the design of pyrobreaker.
The superconducting tokamak device constrains high-temperature plasma through an extremely high magnetic field to achieve a controllable nuclear fusion reaction. To ensure the safe operation of the superconducting magnets, the quench protection system relies on pyrobreaker for critical backup protection. In this paper, the numerical model of current contacts in the 15 kV pyrobreaker has been established and the analysis is carried out for the contact breaking process. The detonation pressure required for contact separation and the pressure distribution law generated by the explosion are calculated. Furthermore, the accuracy of the numerical simulations is verified through experimental validation, providing a theoretical foundation for the design of pyrobreaker.
2024, 36: 115021.
doi: 10.11884/HPLPB202436.240234
Abstract:
Stacked Blumlein pulse generators have the advantages of being flexible and compact, however, switch isolation issue hinders its applications. In this paper, an all-solid-state stacked Blumlein pulse generator is designed. A 4-winding common-mode inductor is used for charging the pulse-forming network, supplying driver circuit and isolating high-voltage. Firstly, the principle of isolation is analysed, an isolated trigger assembly containing common mode inductor and synchronous optical trigger is designed, the charging and discharging process of the stacked Blumlein pulse generator is analysed, and a Blumlein pulse forming network based on IGBT switch arrays is designed; secondly, simulation is carried out on the designed Blumlein pulse forming network and stacked Blumlein pulse generator, and 8-winding common mode inductors are used as the pulse forming network to drive the power supply and high voltage isolation device. Ultimately, an 8-stage stacked Blumlein pulse generator experiment was carried out, and a square wave pulse with a voltage of 30.0 kV, a current of 604 A, and a pulse width of 237 ns was obtained on a matched load.
Stacked Blumlein pulse generators have the advantages of being flexible and compact, however, switch isolation issue hinders its applications. In this paper, an all-solid-state stacked Blumlein pulse generator is designed. A 4-winding common-mode inductor is used for charging the pulse-forming network, supplying driver circuit and isolating high-voltage. Firstly, the principle of isolation is analysed, an isolated trigger assembly containing common mode inductor and synchronous optical trigger is designed, the charging and discharging process of the stacked Blumlein pulse generator is analysed, and a Blumlein pulse forming network based on IGBT switch arrays is designed; secondly, simulation is carried out on the designed Blumlein pulse forming network and stacked Blumlein pulse generator, and 8-winding common mode inductors are used as the pulse forming network to drive the power supply and high voltage isolation device. Ultimately, an 8-stage stacked Blumlein pulse generator experiment was carried out, and a square wave pulse with a voltage of 30.0 kV, a current of 604 A, and a pulse width of 237 ns was obtained on a matched load.
2024, 36: 115022.
doi: 10.11884/HPLPB202436.240252
Abstract:
The delayed breakdown characteristic is crucial for achieving the rapid conduction in PIN diodes. This paper addresses the challenges associated with analyzing the physical process involved in delayed breakdown conduction, primarily due to its short duration. An integrated diode model based on the PIN structure has been designed and validated in the study. Firstly, a numerical simulation model of the diode was developed using TCAD. The simulation results indicated that, influenced by a rapid rising high-voltage trigger pulse with a rise time of 520 V/ns and a magnitude of1000 V, the breakdown voltage of the diode could reach 1.76 times its static reverse breakdown voltage. The accuracy of the established model was further verified by examining changes in the carrier concentration and the evolution of the internal electric field during the conduction process. Secondly, based on bipolar carrier diffusion theory and the parameters obtained from TCAD simulations, the base region parameters of the diode were processed using the Laplace transform and Pade approximation method for equivalent circuit representation. Finally, utilizing the equivalent circuit parameters of the base region and considering conductance modulation effects, an integrated model of the PIN diode was constructed based on its delayed breakdown characteristics. This model was simulated and verified in Pspice software, demonstrating that under the same triggering pulse, the conduction process of the diode device is basically consistent with the TCAD simulation results. This study provides a straightforward and effective circuit analytic method for exploring the reverse delayed breakdown characteristics in rapidly conducting diodes.
The delayed breakdown characteristic is crucial for achieving the rapid conduction in PIN diodes. This paper addresses the challenges associated with analyzing the physical process involved in delayed breakdown conduction, primarily due to its short duration. An integrated diode model based on the PIN structure has been designed and validated in the study. Firstly, a numerical simulation model of the diode was developed using TCAD. The simulation results indicated that, influenced by a rapid rising high-voltage trigger pulse with a rise time of 520 V/ns and a magnitude of
2024, 36: 115023.
doi: 10.11884/HPLPB202436.240316
Abstract:
To address the issues of low repetition frequency and short lifespan associated with the traditional thyratron half-sine pulse power supply used in accelerators, a new half-sine type inductive adder pulse power supply based on LC resonance was developed. The pulse generation is controlled by two types of switches: IGBTs in the primary side of the transformer serve as the active pulse turn-on switch, while the secondary side high-voltage silicon stack acts as the passive pulse turn-off switch. This design increases the possibility of using high-power IGBT with long turn-off delay in narrow pulse applications. By utilizing the saturation characteristic of the transformer core, the energy of the storage capacitor is self-supplied through reverse resonance in the primary side of the adder, reducing the circuit's charging time and thermal loss. By combining PSpice simulation and circuit experiments, a prototype of a 5-layer stack pulse power supply was developed and tested under different parameters. Experimental results have shown that compared to the traditional thyratron half-sine pulse power supply, this pulse power supply can achieve higher pulse repetition frequency and lower power loss.
To address the issues of low repetition frequency and short lifespan associated with the traditional thyratron half-sine pulse power supply used in accelerators, a new half-sine type inductive adder pulse power supply based on LC resonance was developed. The pulse generation is controlled by two types of switches: IGBTs in the primary side of the transformer serve as the active pulse turn-on switch, while the secondary side high-voltage silicon stack acts as the passive pulse turn-off switch. This design increases the possibility of using high-power IGBT with long turn-off delay in narrow pulse applications. By utilizing the saturation characteristic of the transformer core, the energy of the storage capacitor is self-supplied through reverse resonance in the primary side of the adder, reducing the circuit's charging time and thermal loss. By combining PSpice simulation and circuit experiments, a prototype of a 5-layer stack pulse power supply was developed and tested under different parameters. Experimental results have shown that compared to the traditional thyratron half-sine pulse power supply, this pulse power supply can achieve higher pulse repetition frequency and lower power loss.
2024, 36: 115024.
doi: 10.11884/HPLPB202436.240330
Abstract:
The avalanche transistor-based Marx circuit is often used to generate high-voltage nanosecond pulses, its output waveform usually has a rising time about hundreds of picoseconds, an exponential discharging falling edge, and an output voltage in kV-level. However, the typical output waveform falling edge of this circuit structure usually has oscillation or distortion. Meanwhile, as long as the main capacitance of Marx circuit is large enough, the spike oscillation would emerge in the rising edge of the output waveform. Previous studies have paid less attention to this or attributed it to the influence of circuit stray parameters and impedance matching. In this paper, the simulation analysis was carried out from the perspective of the dynamic switching process of the avalanche transistor, and the influences of the main capacitor, the number of Marx circuit stages and the charging voltage were studied experimentally. The results show that the operating state of the avalanche transistor in voltage ramp mode caused the waveform oscillation. The oscillation would be more obvious when the circuit has larger main capacitance, fewer Marx stages and lower charging voltage. Moreover, the amplitude of the pulse oscillation could even be higher than the fast front edge, at this time, the fast front edge could be regarded as the spike oscillation in the output waveform rising edge. The output waveform oscillation can be reduced by adjusting the main capacitance of Marx circuit and optimizing the structure of microstrip line.
The avalanche transistor-based Marx circuit is often used to generate high-voltage nanosecond pulses, its output waveform usually has a rising time about hundreds of picoseconds, an exponential discharging falling edge, and an output voltage in kV-level. However, the typical output waveform falling edge of this circuit structure usually has oscillation or distortion. Meanwhile, as long as the main capacitance of Marx circuit is large enough, the spike oscillation would emerge in the rising edge of the output waveform. Previous studies have paid less attention to this or attributed it to the influence of circuit stray parameters and impedance matching. In this paper, the simulation analysis was carried out from the perspective of the dynamic switching process of the avalanche transistor, and the influences of the main capacitor, the number of Marx circuit stages and the charging voltage were studied experimentally. The results show that the operating state of the avalanche transistor in voltage ramp mode caused the waveform oscillation. The oscillation would be more obvious when the circuit has larger main capacitance, fewer Marx stages and lower charging voltage. Moreover, the amplitude of the pulse oscillation could even be higher than the fast front edge, at this time, the fast front edge could be regarded as the spike oscillation in the output waveform rising edge. The output waveform oscillation can be reduced by adjusting the main capacitance of Marx circuit and optimizing the structure of microstrip line.
