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2024, 36: 055001.
doi: 10.11884/HPLPB202436.240053
2024, 36: 055004.
doi: 10.11884/HPLPB202436.240020
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2024,
36: 1-2.
2024,
36: 055001.
doi: 10.11884/HPLPB202436.240053
Abstract:
This review article aims at summarizing the basic principles of circuit methods used in compact pulsed-power generators. The concept of energy storage and voltage adding are explained followed by the descriptions on switching unit design and control signal generation. Some examples of applications of these circuit methods are given, including Marx circuit using capacitor energy storage, Marx circuit using inductive energy storage, Marx circuit using hybrid energy storage, linear transformer driver (LTD) circuit using capacitive energy storage and LTD circuit using inductive energy storage.
This review article aims at summarizing the basic principles of circuit methods used in compact pulsed-power generators. The concept of energy storage and voltage adding are explained followed by the descriptions on switching unit design and control signal generation. Some examples of applications of these circuit methods are given, including Marx circuit using capacitor energy storage, Marx circuit using inductive energy storage, Marx circuit using hybrid energy storage, linear transformer driver (LTD) circuit using capacitive energy storage and LTD circuit using inductive energy storage.
2024,
36: 055002.
doi: 10.11884/HPLPB202436.230341
Abstract:
An off-line calibration platform is designed based on the requirement of off-line calibration of induction cavity azimuthal transmission line current probe. The analog device is a flat-plate transmission line structure, which has lower distortion than on-line calibration. The source of cross-platform calibration error is analyzed, and the measures to reduce the error are put forward. The analysis shows that the installation eccentricity and probe longitudinal installation depth are the biggest sources of cross-platform calibration error, which need to be paid attention to in engineering design. An off-line calibration platform is established and the error analysis is carried out. As a result, 3.3% cross-platform calibration error is obtained.
An off-line calibration platform is designed based on the requirement of off-line calibration of induction cavity azimuthal transmission line current probe. The analog device is a flat-plate transmission line structure, which has lower distortion than on-line calibration. The source of cross-platform calibration error is analyzed, and the measures to reduce the error are put forward. The analysis shows that the installation eccentricity and probe longitudinal installation depth are the biggest sources of cross-platform calibration error, which need to be paid attention to in engineering design. An off-line calibration platform is established and the error analysis is carried out. As a result, 3.3% cross-platform calibration error is obtained.
2024,
36: 055003.
doi: 10.11884/HPLPB202436.230360
Abstract:
To increase the output voltage and reduce the volume and cost of the high voltage damped oscillator, a 4×4 stage self-triggering Marx structure damped oscillator model is established in this paper. In this model, the main switch of each stage adopts series IGBTs module based on capacitor trigger mode. Only one isolated signal is provided to control the turn-on and turn-off of the primary discharge switch tube. The grid of the adjacent discharge tube is automatically charged and discharged through the interstage capacitance to make it turn-on and turn-off. The model improves the working voltage of Marx single stage and simplifies the driving circuit of each stage, and solves the problem of dynamic and static voltage equalization of switching tube by adding buffer circuit. Based on this topology, a prototype of a high-voltage damped oscillator is built, which outputs 16 kV damped oscillation waveform with a frequency of 1 MHz on an inductive load. The rise time of the waveform is about 75 ns, and the repetition frequency is 500 Hz. The prototype is small in size and stable in operation, which verifies the feasibility of the scheme.
To increase the output voltage and reduce the volume and cost of the high voltage damped oscillator, a 4×4 stage self-triggering Marx structure damped oscillator model is established in this paper. In this model, the main switch of each stage adopts series IGBTs module based on capacitor trigger mode. Only one isolated signal is provided to control the turn-on and turn-off of the primary discharge switch tube. The grid of the adjacent discharge tube is automatically charged and discharged through the interstage capacitance to make it turn-on and turn-off. The model improves the working voltage of Marx single stage and simplifies the driving circuit of each stage, and solves the problem of dynamic and static voltage equalization of switching tube by adding buffer circuit. Based on this topology, a prototype of a high-voltage damped oscillator is built, which outputs 16 kV damped oscillation waveform with a frequency of 1 MHz on an inductive load. The rise time of the waveform is about 75 ns, and the repetition frequency is 500 Hz. The prototype is small in size and stable in operation, which verifies the feasibility of the scheme.
2024,
36: 055004.
doi: 10.11884/HPLPB202436.240020
Abstract:
Flash X-ray radiography is often used to photograph the internal structure and hydrodynamic behavior of high-speed moving objects, and has gradually expanded to the fields of industrial flaw detection, precision system state detection and so on. This paper summarizes the research process and progress of small flash X-ray machine (SFXM), relating to four main technical routes of Marx generator, pulse forming line, fast pulse linear transformer, high-voltage transformer, and two key components of X-ray diode and switches. The research status of small flash X-ray radiography system is discussed, and the shortcomings of mature commercial small X-ray machines abroad and domestic commercial products are explored, The development trend of SFXM in the future is analyzed, which provides reference and basis for the research and development of SFXM and the exploration of commercial popularization.
Flash X-ray radiography is often used to photograph the internal structure and hydrodynamic behavior of high-speed moving objects, and has gradually expanded to the fields of industrial flaw detection, precision system state detection and so on. This paper summarizes the research process and progress of small flash X-ray machine (SFXM), relating to four main technical routes of Marx generator, pulse forming line, fast pulse linear transformer, high-voltage transformer, and two key components of X-ray diode and switches. The research status of small flash X-ray radiography system is discussed, and the shortcomings of mature commercial small X-ray machines abroad and domestic commercial products are explored, The development trend of SFXM in the future is analyzed, which provides reference and basis for the research and development of SFXM and the exploration of commercial popularization.
2024,
36: 055005.
doi: 10.11884/HPLPB202436.230306
Abstract:
With the increasing and extensive applications of high-voltage nanosecond solid-state pulse generators in various fields such as biology, industry, and environment, the pulse waveform, voltage amplitude, pulse duration, and pulse repetition frequency have become essential controllable variables for specific pulse power applications. To further reduce the size and cost of the pulsed power supply, a high-voltage nanosecond pulse modulator with high repetition frequency is proposed with positive Marx circuit, drivers with multiple pulse transformers as the core, and ns rising time. This driver enables the design of a high-voltage nanosecond pulse modulator with ns-level rise time and high repetition frequency. The proposed driver features a compact structure and eliminates the need for multiple isolated power supplies for driving. It allows the gate voltage of two MOSFETs to rise and fall rapidly and synchronously at a high repetition frequency, enabling the generation of gate voltage with controllable amplitude within one hundred nanoseconds. In the case, not only the maximum pulse width is not limited by the magnetic core saturation, but also the negative bias voltage can reliably turn off the switch, improving the reliability of the circuit. In addition, the influence of different turns and magnetic core materials on the driving waveform is studied. A 14-stage pulse modulator prototype is developed. Test results show that the output voltage and pulse width of the modulator based on the drivers are continuously adjustable, with the ability to change the pulse profile. The maximum output voltage reaches 5.5 kV with 100 ns to 50 ms width, minimum rise time of approximately 18 ns, and a continuous repetition frequency of 100 kHz.
With the increasing and extensive applications of high-voltage nanosecond solid-state pulse generators in various fields such as biology, industry, and environment, the pulse waveform, voltage amplitude, pulse duration, and pulse repetition frequency have become essential controllable variables for specific pulse power applications. To further reduce the size and cost of the pulsed power supply, a high-voltage nanosecond pulse modulator with high repetition frequency is proposed with positive Marx circuit, drivers with multiple pulse transformers as the core, and ns rising time. This driver enables the design of a high-voltage nanosecond pulse modulator with ns-level rise time and high repetition frequency. The proposed driver features a compact structure and eliminates the need for multiple isolated power supplies for driving. It allows the gate voltage of two MOSFETs to rise and fall rapidly and synchronously at a high repetition frequency, enabling the generation of gate voltage with controllable amplitude within one hundred nanoseconds. In the case, not only the maximum pulse width is not limited by the magnetic core saturation, but also the negative bias voltage can reliably turn off the switch, improving the reliability of the circuit. In addition, the influence of different turns and magnetic core materials on the driving waveform is studied. A 14-stage pulse modulator prototype is developed. Test results show that the output voltage and pulse width of the modulator based on the drivers are continuously adjustable, with the ability to change the pulse profile. The maximum output voltage reaches 5.5 kV with 100 ns to 50 ms width, minimum rise time of approximately 18 ns, and a continuous repetition frequency of 100 kHz.
2024,
36: 055006.
doi: 10.11884/HPLPB202436.230295
Abstract:
LC series resonant high voltage constant current charging power supply can realize high efficiency and fast charging of the capacitor and has an excellent capacity of anti-load short-circuit, hence it has extensive application prospects in high repetition frequency pulsed power systems. The efficiency of the charging power supply is a crucial factor to determine the ability of the system to operate at repetition rate. Improving efficiency is the primary goal of designing high-voltage capacitor charging power supply. According to the working principle of LC series resonant circuit, it is analyzed that the operating mode of power supply, the switching frequency of the inverter bridge and the distribution parameters of the high-frequency transformer are the main ingredients affecting the efficiency. For a DC power supply with a power of 10 kW and an output voltage of 40 kV, the main circuit parameters were calculated and the circuit model was established using Pspice to verify its accuracy. The soft switching technology was used to reduce the switching loss, and the high frequency transformer with smaller distribution parameters was designed to further improve the efficiency. On this basis, the overall structure design of the power supply was completed. Finally, the charging characteristics of the power supply were tested. Experimental tests indicate that the power supply can charge a 0.1 µF capacitor to 39.5 kV within 37 ms, and the charging efficiency of the power supply is 87.1%.
LC series resonant high voltage constant current charging power supply can realize high efficiency and fast charging of the capacitor and has an excellent capacity of anti-load short-circuit, hence it has extensive application prospects in high repetition frequency pulsed power systems. The efficiency of the charging power supply is a crucial factor to determine the ability of the system to operate at repetition rate. Improving efficiency is the primary goal of designing high-voltage capacitor charging power supply. According to the working principle of LC series resonant circuit, it is analyzed that the operating mode of power supply, the switching frequency of the inverter bridge and the distribution parameters of the high-frequency transformer are the main ingredients affecting the efficiency. For a DC power supply with a power of 10 kW and an output voltage of 40 kV, the main circuit parameters were calculated and the circuit model was established using Pspice to verify its accuracy. The soft switching technology was used to reduce the switching loss, and the high frequency transformer with smaller distribution parameters was designed to further improve the efficiency. On this basis, the overall structure design of the power supply was completed. Finally, the charging characteristics of the power supply were tested. Experimental tests indicate that the power supply can charge a 0.1 µF capacitor to 39.5 kV within 37 ms, and the charging efficiency of the power supply is 87.1%.
2024,
36: 055007.
doi: 10.11884/HPLPB202436.240022
Abstract:
The repetitive narrow pulse signal generator with a sub-nanosecond front, high-voltage amplitude, and approximately Gaussian single-cycle waveform is extensively applied in areas such as ultra-wideband detection and electromagnetic compatibility testing. This paper introduces the design of an all-solid-state repetitive pulse generator utilizing a Marx circuit architecture, which incorporates components like mica capacitors, avalanche transistors, surface-mount technology resistors, and inductors. To meet the signal output specifications, the printed circuit board layout and microstrip lines have been optimized. Through fine-tuning the matching circuit element parameters, the generator successfully delivers a unipolar negative pulse signal with a peak value of approximately 1 kV, a pulse width of around 650 ps, a leading edge of approximately 450 ps, and a trailing edge of about 700 ps across a 50 Ω resistive load. The resulting pulse waveform exhibits similar, smooth, and steep leading and trailing edges, achieving a repetition rate of 10 kHz. Both the peak value and full width at half maximum jitters are maintained at less than 10%.
The repetitive narrow pulse signal generator with a sub-nanosecond front, high-voltage amplitude, and approximately Gaussian single-cycle waveform is extensively applied in areas such as ultra-wideband detection and electromagnetic compatibility testing. This paper introduces the design of an all-solid-state repetitive pulse generator utilizing a Marx circuit architecture, which incorporates components like mica capacitors, avalanche transistors, surface-mount technology resistors, and inductors. To meet the signal output specifications, the printed circuit board layout and microstrip lines have been optimized. Through fine-tuning the matching circuit element parameters, the generator successfully delivers a unipolar negative pulse signal with a peak value of approximately 1 kV, a pulse width of around 650 ps, a leading edge of approximately 450 ps, and a trailing edge of about 700 ps across a 50 Ω resistive load. The resulting pulse waveform exhibits similar, smooth, and steep leading and trailing edges, achieving a repetition rate of 10 kHz. Both the peak value and full width at half maximum jitters are maintained at less than 10%.
2024,
36: 055008.
doi: 10.11884/HPLPB202436.240045
Abstract:
This paper proposes a design method for a high-power pulsed power supply for YAG laser systems, which is capable of realizing high-energy repetitive pulse with flexible voltage regulations. The power supply consists of an LC resonant converter as the charging network and a thyristor-based pulse forming network. Based on the proposed design approach, a 7 kW prototype is developed, which is able to output maximum voltage of 2.2 kV with a repetitive frequency ranged from 1 to 10 Hz. Moreover, the developed power supply is able to release up to 700 J of the energy on the xenon lamp.
This paper proposes a design method for a high-power pulsed power supply for YAG laser systems, which is capable of realizing high-energy repetitive pulse with flexible voltage regulations. The power supply consists of an LC resonant converter as the charging network and a thyristor-based pulse forming network. Based on the proposed design approach, a 7 kW prototype is developed, which is able to output maximum voltage of 2.2 kV with a repetitive frequency ranged from 1 to 10 Hz. Moreover, the developed power supply is able to release up to 700 J of the energy on the xenon lamp.
2024,
36: 055009.
doi: 10.11884/HPLPB202436.230420
Abstract:
Flash X-ray photography technology has important scenarios in military and civil fields. According to the requirement of high repetition rate of the linear induction a ccelerator, we put foruarc a pulse power source scheme based on tri-coaxial cable Blumlein lines driven by hydrogen thyratron. A tri-coaxial cable was designed and developed. The conduction characteristics of hydrogen thyratron were studied. The verification setup for the pulse power source was built. The experimental research on kHz repetition rate pulse power source and kHz repetition rate pulse power source driving induction cavity was carried out. The results show that the tri-coaxial cable Blumlein lines pulse power source driven by hydrogen thyratron can realize the kHz repetition rate square wave output with excellent waveform quality.
Flash X-ray photography technology has important scenarios in military and civil fields. According to the requirement of high repetition rate of the linear induction a ccelerator, we put foruarc a pulse power source scheme based on tri-coaxial cable Blumlein lines driven by hydrogen thyratron. A tri-coaxial cable was designed and developed. The conduction characteristics of hydrogen thyratron were studied. The verification setup for the pulse power source was built. The experimental research on kHz repetition rate pulse power source and kHz repetition rate pulse power source driving induction cavity was carried out. The results show that the tri-coaxial cable Blumlein lines pulse power source driven by hydrogen thyratron can realize the kHz repetition rate square wave output with excellent waveform quality.
2024,
36: 055010.
doi: 10.11884/HPLPB202436.230347
Abstract:
To meet the requirements of multi-channel precise synchronous trigger switch, photo conductive semiconductor switch (PCSS) is combined with V/N gas switch, which takes advantage of the photoelectric isolation, low trigger threshold, low delay time jitter and photoelectric isolation of PCSS, as well as the advantages of high operating voltage and strong load capacity of V/N gas switch. The core of the combination of the two switches is that the structural parameters of the V/N gas switch match the parameters of the PCSS trigger loop. The structural capacitance, trigger loop oscillation parameters and switching electric field distribution of the V/N gas switch are analyzed and calculated. The relationship between the structural capacitance of the V/N gas switch and the oscillation loop composed of PCSS and series inductors is studied. The self-breakdown voltage curve, on-delay time and delay time jitter of the switch under different under voltage ratios are obtained. The performance of the V/N gas switch for PCSS triggering is preliminarily verified.
To meet the requirements of multi-channel precise synchronous trigger switch, photo conductive semiconductor switch (PCSS) is combined with V/N gas switch, which takes advantage of the photoelectric isolation, low trigger threshold, low delay time jitter and photoelectric isolation of PCSS, as well as the advantages of high operating voltage and strong load capacity of V/N gas switch. The core of the combination of the two switches is that the structural parameters of the V/N gas switch match the parameters of the PCSS trigger loop. The structural capacitance, trigger loop oscillation parameters and switching electric field distribution of the V/N gas switch are analyzed and calculated. The relationship between the structural capacitance of the V/N gas switch and the oscillation loop composed of PCSS and series inductors is studied. The self-breakdown voltage curve, on-delay time and delay time jitter of the switch under different under voltage ratios are obtained. The performance of the V/N gas switch for PCSS triggering is preliminarily verified.
2024,
36: 055011.
doi: 10.11884/HPLPB202436.240040
Abstract:
The working characteristics of the hydrogen thyratron and the optimization effect of the potential equalization treatment are investigated experimentally. The experiments show that the heating voltage has great influence on the working characteristics of hydrogen thyratron, on the premise of no self-discharge phenomenon, using higher heating voltage can obtain better conduction performance. The differences of trigger pulses and anode voltages have little effect on the conduction performance of hydrogen thyratron. Using resistors to equalize the voltage of hydrogen thyratron can make the voltage distribution more uniform and alleviate the phenomenon of self-discharge. The research provides reference and guidance for the use of hydrogen thyratron.
The working characteristics of the hydrogen thyratron and the optimization effect of the potential equalization treatment are investigated experimentally. The experiments show that the heating voltage has great influence on the working characteristics of hydrogen thyratron, on the premise of no self-discharge phenomenon, using higher heating voltage can obtain better conduction performance. The differences of trigger pulses and anode voltages have little effect on the conduction performance of hydrogen thyratron. Using resistors to equalize the voltage of hydrogen thyratron can make the voltage distribution more uniform and alleviate the phenomenon of self-discharge. The research provides reference and guidance for the use of hydrogen thyratron.
2024,
36: 055012.
doi: 10.11884/HPLPB202436.240036
Abstract:
The pseudospark switch works in the left branch of Paschen curve with low gas pressure, and it has the advantages of ns-level breakdown time, 100 kA-level pulse current and long lifetime. High pulse repetition frequency (PRF) pseudospark switch are widely used in both civil and military fields. This paper focuses on the double-pulse trigger structure and presents the design of a switch with this structure, which is tested with 10 kV anode voltage for different gas pressure, pre-trigger voltage and main trigger voltage. The corresponding relationship between the gas pressure, the two trigger voltages and trigger current are calculated respectively. In addition, the influence of pre-trigger and main trigger pulses on the trigger process is analysed. The results show that the minimum trigger voltage is only 100 V, and the switch can work stably with high repetition frequency.
The pseudospark switch works in the left branch of Paschen curve with low gas pressure, and it has the advantages of ns-level breakdown time, 100 kA-level pulse current and long lifetime. High pulse repetition frequency (PRF) pseudospark switch are widely used in both civil and military fields. This paper focuses on the double-pulse trigger structure and presents the design of a switch with this structure, which is tested with 10 kV anode voltage for different gas pressure, pre-trigger voltage and main trigger voltage. The corresponding relationship between the gas pressure, the two trigger voltages and trigger current are calculated respectively. In addition, the influence of pre-trigger and main trigger pulses on the trigger process is analysed. The results show that the minimum trigger voltage is only 100 V, and the switch can work stably with high repetition frequency.
2024,
36: 055013.
doi: 10.11884/HPLPB202436.230371
Abstract:
To reduce the jitter of the direct current self-breakdown voltage, and not affect the self-breakdown voltage as much as possible, an auxiliary discharge electrode structure with an auxiliary discharge needle implanted in the cathode center is designed based on the discharge gap of the annular electrode. The influence of the diameter, length and top chamfer of the auxiliary discharge needle on the field distortion is studied by electric field simulation. The direct current self-breakdown characteristics of the gas gap without and with auxiliary discharge needle in dry air and SF6 gas are studied by experiments. The results show that the smaller the diameter and the longer the length of the auxiliary discharge needle, the weaker the shielding effect of the electrode ring on the electric field, the stronger the field distortion intensity; the influence of the implatation of auxiliary discharge needle on the direct current self-breakdown of SF6 gas discharge gap is small, and with the increase of the field distortion coefficient, the percentage drop of self-breakdown voltage of dry air at the same air pressure is 2-3 times that of SF6 gas; the auxiliary discharge needle has a beneficial effect on the breakdown stability of dry air and SF6 gas discharge gap under the condition of direct current , the dispersion reduction percentage is about 25% higher than that without auxiliary discharge needle.
To reduce the jitter of the direct current self-breakdown voltage, and not affect the self-breakdown voltage as much as possible, an auxiliary discharge electrode structure with an auxiliary discharge needle implanted in the cathode center is designed based on the discharge gap of the annular electrode. The influence of the diameter, length and top chamfer of the auxiliary discharge needle on the field distortion is studied by electric field simulation. The direct current self-breakdown characteristics of the gas gap without and with auxiliary discharge needle in dry air and SF6 gas are studied by experiments. The results show that the smaller the diameter and the longer the length of the auxiliary discharge needle, the weaker the shielding effect of the electrode ring on the electric field, the stronger the field distortion intensity; the influence of the implatation of auxiliary discharge needle on the direct current self-breakdown of SF6 gas discharge gap is small, and with the increase of the field distortion coefficient, the percentage drop of self-breakdown voltage of dry air at the same air pressure is 2-3 times that of SF6 gas; the auxiliary discharge needle has a beneficial effect on the breakdown stability of dry air and SF6 gas discharge gap under the condition of direct current , the dispersion reduction percentage is about 25% higher than that without auxiliary discharge needle.
2024,
36: 055014.
doi: 10.11884/HPLPB202436.230392
Abstract:
The breakdown characteristics of trigger gap for the pre-ionization switch in N2, the mixture of N2 and SF6 and SF6 atmosphere under positive and negative pulse were investigated for the higher voltage grade and bipolarity application. The relationships between the breakdown voltage and delay time of the pre-ionization gap and the pressure of different kinds of gases were obtained, and the breakdown characteristics were compared for the pre-ionization gap under positive and negative polarities. The results of the experiment demonstrated that the breakdown process of the gap in N2 was more stable, and the linearity of breakdown voltage varying with pressure in N2 was the best among the three kinds of gases. The breakdown voltage was saturated only in SF6 with the increase of gas pressure. The breakdown voltage of the gap under negative polarity was higher than that under the positive at some certain values of the pressure, and this phenomenon might suggest that there was a polarity effect upon the breakdown process of pre-ionization gap. Compared with the mixture and N2, the absolute differences between negative and positive polarity for both breakdown voltage and delay time in SF6 were relatively higher. N2 should be preferred as the insulating medium for the pre-ionization gap to reduce the synchronization delay difference of the bipolar self-triggered switches. The polarity effect of the pre-ionization gap and the distinctions among the different kinds of insulated gas medium should be paid more attention in engineering applications for the pre-ionization gap.
The breakdown characteristics of trigger gap for the pre-ionization switch in N2, the mixture of N2 and SF6 and SF6 atmosphere under positive and negative pulse were investigated for the higher voltage grade and bipolarity application. The relationships between the breakdown voltage and delay time of the pre-ionization gap and the pressure of different kinds of gases were obtained, and the breakdown characteristics were compared for the pre-ionization gap under positive and negative polarities. The results of the experiment demonstrated that the breakdown process of the gap in N2 was more stable, and the linearity of breakdown voltage varying with pressure in N2 was the best among the three kinds of gases. The breakdown voltage was saturated only in SF6 with the increase of gas pressure. The breakdown voltage of the gap under negative polarity was higher than that under the positive at some certain values of the pressure, and this phenomenon might suggest that there was a polarity effect upon the breakdown process of pre-ionization gap. Compared with the mixture and N2, the absolute differences between negative and positive polarity for both breakdown voltage and delay time in SF6 were relatively higher. N2 should be preferred as the insulating medium for the pre-ionization gap to reduce the synchronization delay difference of the bipolar self-triggered switches. The polarity effect of the pre-ionization gap and the distinctions among the different kinds of insulated gas medium should be paid more attention in engineering applications for the pre-ionization gap.
2024,
36: 055015.
doi: 10.11884/HPLPB202436.230337
Abstract:
Based on the requirement of high current multi-pulse accelerator, the surface flashover characteristics of cross-linked polystyrene (XLPS) material under burst multi-pulse in vacuum were studied experimentally. Vacuum surface flashover experiments were carried out with XLPS samples placed in flat electrodes under single pulse and three pulses with interval of 500 ns. Special phenomena such as continuous decrease of equivalent impedance of vacuum surface before flashover and continuous maintenance of flashover channel after pulse end were observed, and statistical data of vacuum surface flashover of XLPS materials under corresponding conditions were obtained. On the basis of experiments, the flashover characteristics of XLPS in vacuum under high repetition rate multi-pulse loading are analyzed, which provides experimental basis for insulation design of high repetition rate multi-pulse accelerator.
Based on the requirement of high current multi-pulse accelerator, the surface flashover characteristics of cross-linked polystyrene (XLPS) material under burst multi-pulse in vacuum were studied experimentally. Vacuum surface flashover experiments were carried out with XLPS samples placed in flat electrodes under single pulse and three pulses with interval of 500 ns. Special phenomena such as continuous decrease of equivalent impedance of vacuum surface before flashover and continuous maintenance of flashover channel after pulse end were observed, and statistical data of vacuum surface flashover of XLPS materials under corresponding conditions were obtained. On the basis of experiments, the flashover characteristics of XLPS in vacuum under high repetition rate multi-pulse loading are analyzed, which provides experimental basis for insulation design of high repetition rate multi-pulse accelerator.
2024,
36: 055016.
doi: 10.11884/HPLPB202436.230410
Abstract:
The study of vacuum surface flashover along the insulator ring was carried out. An experimental platform for vacuum insulator stack was built. The influence of flashover among insulator ring on the voltage of the vacuum insulator stack was evaluated by equivalent circuit model. Vacuum surface flashover along the three kinds of material insulator stacks were carried out, which verify the availability and reliability of the experimental platform. This work provides a reference for the engineering research of the vacuum insulator stack of pulse power device, and also provides an experimental platform for research of new insulation materials.
The study of vacuum surface flashover along the insulator ring was carried out. An experimental platform for vacuum insulator stack was built. The influence of flashover among insulator ring on the voltage of the vacuum insulator stack was evaluated by equivalent circuit model. Vacuum surface flashover along the three kinds of material insulator stacks were carried out, which verify the availability and reliability of the experimental platform. This work provides a reference for the engineering research of the vacuum insulator stack of pulse power device, and also provides an experimental platform for research of new insulation materials.
2024,
36: 055017.
doi: 10.11884/HPLPB202436.230423
Abstract:
In a previous work, a two-stage microstructure was proposed and demonstrated to be able to sharply improve surface flashover voltage of polymer insulators in vacuum. In this paper, the two-stage microstructure was separated into two sub-structures, i.e., surface micro-groove structure and surface micro-hole structure, to study the voltage improvement mechanism in the two-stage microstructure. Through the synthesis of a composite material, laser treatment and acid corrosion, the two-stage microstructure was prepared as well as the two sub-structures. Flashover test of the insulators with the three kinds of surface structures showed that construction of micro grooves and micro holes on the surface of insulators could both enhance the surface flashover strength and their combination could further enhance the flashover strength. The results indicate that through proper combination of different kinds of surface structures multiple suppression of the flashover could be achieved and the surface flashover voltage could be further improved.
In a previous work, a two-stage microstructure was proposed and demonstrated to be able to sharply improve surface flashover voltage of polymer insulators in vacuum. In this paper, the two-stage microstructure was separated into two sub-structures, i.e., surface micro-groove structure and surface micro-hole structure, to study the voltage improvement mechanism in the two-stage microstructure. Through the synthesis of a composite material, laser treatment and acid corrosion, the two-stage microstructure was prepared as well as the two sub-structures. Flashover test of the insulators with the three kinds of surface structures showed that construction of micro grooves and micro holes on the surface of insulators could both enhance the surface flashover strength and their combination could further enhance the flashover strength. The results indicate that through proper combination of different kinds of surface structures multiple suppression of the flashover could be achieved and the surface flashover voltage could be further improved.
2024,
36: 055018.
doi: 10.11884/HPLPB202436.230285
Abstract:
This article investigates the Ricker pulse to address the issue of low radiation efficiency in time-domain antennas. Firstly, it highlights the high center frequency of the Ricker pulse, which is advantageous for improving antenna radiation efficiency. Then it proceeds to explain the power synthesis method for generating Ricker pulses, derives a theoretical formula for the optimal delay of synthesizing high-order Gaussian pulses, starting with precise time delay control. It describes the design of a unipolar pulse and the optimization of its falling edge using the sharpening capacitor method. With this unipolar pulse as a foundation, a Ricker pulse is designed, featuring a peak-to-peak value of 5.1 kV, a main peak half-width of 350 ps, and a center frequency of 0.5 GHz. To verify the correctness of the analysis, the article proposes a simple method to calculate the radiation efficiency of all-metal time-domain antennas. Both the designed Ricker pulse and a unipolar pulse with the same pulse width are used to excite the same antenna. The results demonstrate that the amplitude radiation efficiency of the single-pole pulse is only about 60%. In contrast, the Ricker pulse achieves over 80% efficiency. Similarly, the power radiation efficiency of the single-pole pulse is less than 40%, while that of the Ricker pulse can exceed 60%. The utilization of Ricker pulses as excitation has proven to be highly effective in enhancing the radiation efficiency of antennas, thereby minimizing the potential damage to transmission systems caused by reflected power. Additionally, this technique holds immense value in antenna miniaturization and exhibits promising applications in time-domain technologies like ground penetrating radar and high-power microwave sources.
This article investigates the Ricker pulse to address the issue of low radiation efficiency in time-domain antennas. Firstly, it highlights the high center frequency of the Ricker pulse, which is advantageous for improving antenna radiation efficiency. Then it proceeds to explain the power synthesis method for generating Ricker pulses, derives a theoretical formula for the optimal delay of synthesizing high-order Gaussian pulses, starting with precise time delay control. It describes the design of a unipolar pulse and the optimization of its falling edge using the sharpening capacitor method. With this unipolar pulse as a foundation, a Ricker pulse is designed, featuring a peak-to-peak value of 5.1 kV, a main peak half-width of 350 ps, and a center frequency of 0.5 GHz. To verify the correctness of the analysis, the article proposes a simple method to calculate the radiation efficiency of all-metal time-domain antennas. Both the designed Ricker pulse and a unipolar pulse with the same pulse width are used to excite the same antenna. The results demonstrate that the amplitude radiation efficiency of the single-pole pulse is only about 60%. In contrast, the Ricker pulse achieves over 80% efficiency. Similarly, the power radiation efficiency of the single-pole pulse is less than 40%, while that of the Ricker pulse can exceed 60%. The utilization of Ricker pulses as excitation has proven to be highly effective in enhancing the radiation efficiency of antennas, thereby minimizing the potential damage to transmission systems caused by reflected power. Additionally, this technique holds immense value in antenna miniaturization and exhibits promising applications in time-domain technologies like ground penetrating radar and high-power microwave sources.
2024,
36: 055019.
doi: 10.11884/HPLPB202436.230354
Abstract:
A compact repetitive pulse power source is developed as an experimental platform for high power relativistic magnetron with low magnetic field. To obtain better output pulse waveform with a compact structure, the pulsed power source designed based on PFN-Marx technology has a coaxial structure. A circular pulse forming net (PFN) is devised out with the impedance of 4 Ω, working voltage of 50 kV, and electrical length of 53 ns, consisting of 13 ceramic capacitors with the capacitance of 1nF. Two PFN devices in series by a gas switch and an insulation plate form a circular high-voltage pulse generation module. Multiple pulse generation modules are coaxial and stacked in a metal cylinder. Inductive isolation is used between the modules. After all switches are turned on, all modules are discharged in series to generate a fast rising-time high-power square wave pulse. Moreover, repetitive operation is achieved through synchronous control of the trigger switch and charging power supply. In experiments the 22-stage PFN-Marx pulsed power source developed was charged to 51 kV, and a high-voltage square wave pulse of 516 kV was obtained on a load of 84 Ω, with pulse width (FWHM) of 104 ns, flat top of 63 ns and rising-time of 11 ns. This power source can operate stably at a repetition rate of 20 Hz for 15 s.
A compact repetitive pulse power source is developed as an experimental platform for high power relativistic magnetron with low magnetic field. To obtain better output pulse waveform with a compact structure, the pulsed power source designed based on PFN-Marx technology has a coaxial structure. A circular pulse forming net (PFN) is devised out with the impedance of 4 Ω, working voltage of 50 kV, and electrical length of 53 ns, consisting of 13 ceramic capacitors with the capacitance of 1nF. Two PFN devices in series by a gas switch and an insulation plate form a circular high-voltage pulse generation module. Multiple pulse generation modules are coaxial and stacked in a metal cylinder. Inductive isolation is used between the modules. After all switches are turned on, all modules are discharged in series to generate a fast rising-time high-power square wave pulse. Moreover, repetitive operation is achieved through synchronous control of the trigger switch and charging power supply. In experiments the 22-stage PFN-Marx pulsed power source developed was charged to 51 kV, and a high-voltage square wave pulse of 516 kV was obtained on a load of 84 Ω, with pulse width (FWHM) of 104 ns, flat top of 63 ns and rising-time of 11 ns. This power source can operate stably at a repetition rate of 20 Hz for 15 s.
2024,
36: 055020.
doi: 10.11884/HPLPB202436.240042
Abstract:
High-altitude electromagnetic pulse (HEMP), as a wide-area electromagnetic attack method, can have severe impacts on the power equipment and even collapse the power infrastructure, posing significant challenges to the electromagnetic safety of novel power systems. This article focuses on the latest research progress on the power system effects in late-time HEMP environment. Firstly, the mechanism of geomagnetic disturbance generation and the calculation method of induced geomagnetic field are analyzed. The calculation method of geomagnetically induced current (GIC) is provided. Then, the effects and mechanisms of typical primary power equipment, such as power transformers, current transformers, circuit breakers, etc. under extreme GIC conditions are summarized. Next, the extreme GIC injection devices and simulated experiment methods are discussed. And the experimental and simulation results acquired by Defense Threat Reduction Agency (DTRA) and Electric Power Research Institute (EPRI) are also discussed, as well as the power system effects simulation and assessment. Finally, the article summarises the present work, and analyzes the future research from the perspective of effects mechanism, primary power equipment characteristics, simulated experimental methods, and system-level effects assessment.
High-altitude electromagnetic pulse (HEMP), as a wide-area electromagnetic attack method, can have severe impacts on the power equipment and even collapse the power infrastructure, posing significant challenges to the electromagnetic safety of novel power systems. This article focuses on the latest research progress on the power system effects in late-time HEMP environment. Firstly, the mechanism of geomagnetic disturbance generation and the calculation method of induced geomagnetic field are analyzed. The calculation method of geomagnetically induced current (GIC) is provided. Then, the effects and mechanisms of typical primary power equipment, such as power transformers, current transformers, circuit breakers, etc. under extreme GIC conditions are summarized. Next, the extreme GIC injection devices and simulated experiment methods are discussed. And the experimental and simulation results acquired by Defense Threat Reduction Agency (DTRA) and Electric Power Research Institute (EPRI) are also discussed, as well as the power system effects simulation and assessment. Finally, the article summarises the present work, and analyzes the future research from the perspective of effects mechanism, primary power equipment characteristics, simulated experimental methods, and system-level effects assessment.
2024,
36: 055021.
doi: 10.11884/HPLPB202436.230432
Abstract:
Aiming at the difficulty of predicting the length of rock-breaking arc plasma channel by high voltage pulse discharge, a comprehensive test platform for rock-breaking arc plasma channel by high voltage pulse discharge was constructed. The development characteristics and typical current and voltage parameters of arc plasma channel under granite-tap water combined medium were measured, and the broken region formed on the rock surface under different electrode spacing and pulse discharge times was extracted. Based on the energy balance equation, the impedance model of the arc plasma channel in rock is established. The approximate optimal solution of the impedance model parameters is obtained by iterative optimization algorithm. The relative error between the calculated results and the experimental results is less than 7%. Based on the optimized parameters, the length of plasma channel is predicted by the measured current and voltage data. The absolute error between the plasma channel length predicted by the model and the measured value is in the order of mm, and the relative error is less than 10%, which provides theoretical support for the matching design of power-electrode load in the high-voltage pulse discharge rock breaking system.
Aiming at the difficulty of predicting the length of rock-breaking arc plasma channel by high voltage pulse discharge, a comprehensive test platform for rock-breaking arc plasma channel by high voltage pulse discharge was constructed. The development characteristics and typical current and voltage parameters of arc plasma channel under granite-tap water combined medium were measured, and the broken region formed on the rock surface under different electrode spacing and pulse discharge times was extracted. Based on the energy balance equation, the impedance model of the arc plasma channel in rock is established. The approximate optimal solution of the impedance model parameters is obtained by iterative optimization algorithm. The relative error between the calculated results and the experimental results is less than 7%. Based on the optimized parameters, the length of plasma channel is predicted by the measured current and voltage data. The absolute error between the plasma channel length predicted by the model and the measured value is in the order of mm, and the relative error is less than 10%, which provides theoretical support for the matching design of power-electrode load in the high-voltage pulse discharge rock breaking system.
2024,
36: 055022.
doi: 10.11884/HPLPB202436.230342
Abstract:
Aiming at the output characteristics of diesel generator set with pulse load, an index is proposed to evaluate the consistency of output voltage (current) waveform to judge the simulation degree of the model. Also, a dynamic limiting method for synchronous generator excitation voltage output based on BP neural network algorithm is proposed, and it is applied to the model optimization of diesel generator set. Experimental results show that among the 27 sets of examples, 18 groups’ real-time waveform proximity (RWP) values are less than 90% in the original simulation but in the optimized simulation, the RWP values of all the test groups are higher than 90%, indicating that the optimized simulation model is more effective, and can be applied to further research on diesel generator set with pulse load.
Aiming at the output characteristics of diesel generator set with pulse load, an index is proposed to evaluate the consistency of output voltage (current) waveform to judge the simulation degree of the model. Also, a dynamic limiting method for synchronous generator excitation voltage output based on BP neural network algorithm is proposed, and it is applied to the model optimization of diesel generator set. Experimental results show that among the 27 sets of examples, 18 groups’ real-time waveform proximity (RWP) values are less than 90% in the original simulation but in the optimized simulation, the RWP values of all the test groups are higher than 90%, indicating that the optimized simulation model is more effective, and can be applied to further research on diesel generator set with pulse load.
2024,
36: 055023.
doi: 10.11884/HPLPB202436.230422
Abstract:
To investigate the spatial distribution characteristics of active particles in atmospheric pressure pulse driven plasma jet, a coaxial double ring plasma jet reactor was used. Under external pulsed power excitation, the relative intensity changes of characteristic peaks of each active particle in different ionization regions along the axial space were studied. The results show that active particle characteristic peaks such as NO, OH, N2,\begin{document}${\rm{N}}_2^{+}$\end{document} ![]()
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To investigate the spatial distribution characteristics of active particles in atmospheric pressure pulse driven plasma jet, a coaxial double ring plasma jet reactor was used. Under external pulsed power excitation, the relative intensity changes of characteristic peaks of each active particle in different ionization regions along the axial space were studied. The results show that active particle characteristic peaks such as NO, OH, N2,
