Repetitive Pulsed Power Generator Research Articles

Solid-State Bipolar Linear Transformer Driver Using Inductive Energy Storage

There have already a lot of circuit topologies for pulsed power generators using semiconductor switches. In this article, a novel circuit topology concept that can generate bipolar pulses based on linear transformer driver (LTD) topology is presented. Different from traditionally capacitive energy storage (CES) method, we utilize magnetic core as inductive energy storage (IES) medium to accumulate inductive energy before releasing pulses. The repetitive bipolar pulsed power generator is capable of operating in high repetition without reset circuit, because positive magnetization and negative magnetization can lead the magnetic core always back to initial state after every period. In this article, a three-stage laboratory prototype of bipolar IES-based LTD is designed and assembled using six existed CES-based LTD modules, which can generate ~2.4 kV bipolar peak pulses, 55 ns pulsewidth on a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$150~\Omega $ </tex-math></inline-formula> resistive load with charging voltage of 80 V. Finally, this proposed three-stage LTD is evaluated under burst mode to verified the high repetition capability of this bipolar IES-based LTD. As a result, this generator can operate at repetitive frequency of 400 kHz without reset.

Recent advances in compact repetitive high-power Marx generators

AbstractThis paper introduces recent activities on Marx-based compact repetitive pulsed power generators at the Institute of Applied Electronics (IAE), China Academy of Engineering Physics (CAEP), over the period 2010–2018. A characteristic feature of the generators described is the use of a simplified bipolar charged Marx circuit, in which the normal isolation resistors or inductors to ground are removed to make the circuit simpler. Several pulse-forming modules developed to generate a 100 ns square wave output are introduced, including thin-film dielectric lines of different structures, a pulse-forming line based on a Printed Circuit Board, and non-uniform pulse-forming networks. A compact repetitive three-electrode spark gap switch with low-jitter, high-voltage, and high-current was developed and is used in the generators. A positive and negative series resonant constant current power supply with high precision and high power is introduced. As an important part of the repetitive pulse power generator, a lower jitter pulse trigger source is introduced. Several typical high-power repetitive pulsed power generators developed at IAE are introduced including a 30 GW low-impedance Marx generator, a compact square-wave pulse generator based on Kapton-film dielectric Blumlein line, a 20 GW high pulse-energy repetitive PFN-Marx generator, and a coaxial Marx generator based on ceramic capacitors. The research of key technologies and their development status are discussed, which can provide a reference for the future development and application of miniaturization of compact and repetitive Marx generators.

Pulsed Voltage Adder Topology Based on Inductive Blumlein Lines

A new scheme of pulsed voltage adding using inductively charged Blumlein lines has been proposed and experimentally demonstrated. The circuit principle is explained based on the analogy with capacitively charged Blumlein lines. In the experiments, striplines have been used for inductive energy storage, and SiC power devices have been used as the opening switches. The experimental results have proved both the circuit behavior and the voltage adding by using multimodule stack. This circuit method is expected to become a new approach to compact and repetitive pulsed-power generation.

High voltage repetitive pulsed power generator by using modular multilevel converter

ABSTRACTThis paper proposes the development of silicon carbide junction field effect transistor-based high-frequency link (HFL) modular multilevel converter (MMC). HFL has been used in conjunction with MMC to achieve higher current density with less foot print, which is the main requirement for exhaust gas treatment. The proposed system has been developed for various scalable ranges such as 6, 8 and 10 modules per arm to generate square wave unipolar/bipolar pulse and exponential decay pulses. These pulses have been generated for 1 kV/cm with 100 µs and 1000 µs and tested. The proposed system has been developed mathematically and simulated in Matlab/Simulink. Thus, obtained results have been verified by conducting an experiment on 3 kV prototype and results are explored.

A Compact Capacitor Charger using Single Chopper for Pulsed Power

In this paper, we miniaturize the capacitor charger for pulsed power applications. The capacitor charger circuit is constructed by a single chopper circuit using a MOSFET (Metal Oxide Semiconductor Field Effect Transistor). A single chopper circuit has many advantages. However, due to operate by single switching device, operating power per switching device is higher than other topology. Then, a SiC (Silicon Carbide)-MOSFET is used for switching device, and compared to a single chopper circuit using a Si (Silicon)-MOSFET. In this research, we simulated a single chopper circuit concisely and developed the miniature capacitor charger for repetitive pulsed power generator. Charging time of Si-MOSFET charger and SiC-MOSFET charger are 310µs and 300µs respectively.

A semiconductor opening switch based generator with pulse repetitive frequency of 4 MHz

A MHz repetitive and nanosecond pulsed power generator based on the semiconductor opening switch (SOS) is developed, in which the pulse compression unit utilizes several Radio Frequency (RF) MOSFETs and a saturable Linear Transformer Driver (LTD). The RF MOSFETs are employed to obtain the forward pumping current pulses with the duration of tens of nanoseconds; the saturable LTD is used to raise the pulse voltage, to compress the pulse width and to pump SOS reversely. The SOS assembly cuts off the reverse current in a few nanoseconds, leading to a narrow output pulse on an external load. The experimental results show that the amplitude of the output pulse on a 106 Ω resistive load is about 3.8 kV and the width is 2 ns. Due to the repetitive ability of the RF MOSFETs, the generator can operate at a repetitive frequency of higher than 4 MHz in burst mode.

高重复频率脉冲功率技术及其应用:(4)半导体开关的特长与局限性

Power semiconductor devices have been used for repetitive pulsed power generation, due to their advantages in stability, reliability, and lifetime. On the other hand, their limitations in power capability and noise vulnerability are expected to be overcome by using various techniques in gate control and circuit configuration. In this paper, some pulse circuit methods to improve the working ability of semiconductor switches are introduced, including using a number of devices in series and parallel, voltage superposition, combination and complementation of switching devices.

Modular, Ultra-compact Marx Generators for Repetitive High-power Microwave Systems

The essential demand for high-power microwave (HPM) devices for both military and civil applications, such as convoy protection and car stopping, requires compact repetitive pulsed-power generators. We report on the latest developments in the technology of our balanced, coaxial Marxtype generators, which distinguish themselves by using a fundamental modular concept for reasons of scalability. The Marx generators especially make use of inductive charging technology to ensure high-repetitive operation. The Marx stages were completely redesigned. Marx generators with a variable number of stages were assembled and successfully tested up to charging voltages of 50 kV for up to 10 stages and up to 40 kV for the 20 stages. Burst mode operation for a duration of 10 s at a pulse repetition frequency of 100 Hz is reported. In order to gain an in-depth insight into the behavior of an inductive Marx generator during the charging and the discharging phases and to derive precise information for the design of future generators, we developed an advanced PSpice simulation model. The breakdown dynamics of the spark gaps was implemented by making use of the Vlastos formula; parasitic eects, such as stray capacitances, were taken into account.

A compact repetitive nanosecond pulsed power generator based on transmission line transformer

In this paper, a compact repetitive nanosecond pulsed power generator based on transmission line transformer (TLT) is developed for non-thermal plasma generation. The high voltage capacitor, the spark gap switch and the input side of the TLT are built into a compact structure to obtain a fast high-power pulse. The properly designed magnetic cores placed around the coaxial cables of the TLT have been chosen to obtain a higher voltage gain. The layout of TLT is optimized to make the generator more compact. Experiment test shows that voltage pulses of 30 kV with rise time of about 25 ns, pulse duration of about 100 ns, pulse repetition rate of 500 pps have been achieved.

All-Solid-State Repetitive Pulsed-Power Generator Using IGBT and Magnetic Compression Switches

By utilizing power semiconductor switches, especially high-voltage insulated gate bipolar transistors (IGBTs), as main switches, Marx modulators have demonstrated many advantages such as variable pulse length and pulse-repetition frequency, snubberless operation, and inherent redundancy. However, the relatively slow turn-on speed of the IGBT influences the pulse rise time of the Marx modulator. In this paper, a newly developed all-solid-state pulsed-power generator is proposed. This generator consists of a Marx modulator based on discrete IGBTs and a magnetic pulse-sharpening circuit, which is employed to compress the rising edge of the Marx output pulse. The experimental results are presented with a maximum voltage of 20 kV, a rise time of 200 ns, a pulse duration of 500 ns (full-width at half-maximum), and a repetition rate of 5 kHz on a 285- resistive load. The output power of the generator is 2.5 kW, and the average power in one pulse is 1 MW. The design methods of the IGBT drive circuits and the parameter calculation of the magnetic pulse-sharpening circuit are introduced in detail in this paper. The factors influencing the performance of the generator are also discussed.

Solid-State LTD Module Using Power MOSFETs

It is proposed that linear transformer driver (LTD) concept can be applied to compact repetitive pulsed-power generation. For experimental demonstration, a table-top LTD module has been constructed by using power metal-oxide-semiconductor field-effect transistors (MOSFETs) and film capacitors. It consists of 24 basic circuits and a magnetic core, contained in a cavity case having a diameter of 32 cm and a height of 1.1 cm. All MOSFETs can be turned on and off synchronously, controlled by a single optic fiber. This LTD module has been tested with operation voltage of 900 V for single shot and 700 V for repetitive operation at 500 Hz. Near-rectangle waveforms were obtained on a resistive load of 3.2 , with pulsewidth of 200 ns, rise time of 20 ns, and fall time of 40 ns. The overall system efficiency was obtained to be 76%.

Recent Developments of Repetitive Pulsed Power Technology

One of the important issues in pulsed power generation is the voltage multiplication. In recent years, several new technologies for voltage multiplication have been developed for compact, repetitive pulsed power generation. This paper summarizes the results of the researches carried out recently on voltage multiplication by using (1) saturable capacitor, (2) compact Marx circuit, and (3) semiconductor opening switch.

An Efficient, Repetitive Nanosecond Pulsed Power Generator with Ten Synchronized Spark Gap Switches

This paper describes an efficient, repetitive nanosecond pulsed power generator using a Transmission-Line-Transformer (TLT) based multiple-switch technology. Within this setup, a 10-stage TLT and ten high-pressure spark-gap switches are adopted. At the input side, ten spark-gap switches are interconnected in series via the TLT, so that all the spark-gap switches can be synchronized automatically. At the output side, all the stages of the TLT are connected in parallel, thus a low output impedance (5 Ω) is obtained, and a large output current is realized by adding the currents through all the switches. Experimental results show that 10 spark-gap switches can be synchronized within about 10 ns. The system has been successfully demonstrated at repetition rates up to 300 pps (Pulses Per Second). Pulses with a rise-time of about 11 ns, a pulse width of about 55 ns, an energy of 9-24 J per pulse, a peak power of 300-810 MW, a peak voltage of 40-77 kV, and a peak current of 6-11 kA have been achieved with an energy conversion efficiency of 93-98%.

Study of an Ultra-Compact, Repetitive Marx Generator for High-Power Microwave Applications

The need for repetitive high-power microwave systems, for instance within the scope of convoy protection, requires the availability of compact, repetitive pulsed-power generators. The development and the first experimental results of an upgraded balanced ISL Marx generator for future repetitive operations at pulse repetition frequencies in the order of 100 Hz are introduced. A key objective is to keep the fundamental modular coaxial concept by reason of its scalability and compactness. Simulation models were developed under the PSpice software package in order to investigate the charging and discharging phases of the Marx generator and also to determine the design criteria for repetitive operations. The charging resistors were replaced by ultracompact inductors for rapid charging, being able to withstand pulsed voltages up to 60 kV and pulsed currents up to 1.4 kA during the discharge phase. An improved type of strontium–titanate high-voltage ceramic capacitor was successfully tested experimentally up to 70 kV. Each new elementary stage of the Marx generator consists of eight 1.1 nF sectors of a cylinder capacitors mounted in parallel, two charging inductors of about 17.8 μH and two halves of spherical spark gaps. The pressurized self-triggered gas switches are arranged along the axis for fast consecutive breakdown thanks to the UV radiation emitted during the breakdown in each gap. The stages are installed in individual fibreglass housings. First experimental results of a 4-stage Marx generator in repetitive operation, driven by a 4 kW capacitor charging power supply up to a maximum voltage of 40 kV, are presented.

Experimental demonstration of relativistic magnetron with modified output configuration

A modified configuration of relativistic magnetron with diffraction output has been investigated experimentally by using repetitive pulsed power generator “ETIGO-IV” (400kV, 13kA, 120ns, 1Hz). The purpose is to verify the improved microwave conversion efficiency predicted by numerical simulations [M. Daimon and W. Jiang, Appl. Phys. Lett. 91, 191503 (2007)]. The experiments have concentrated on comparison between the output microwave powers obtained by using the modified and the conventional configurations of relativistic magnetron. The results have been in general agreement with that obtained by the simulations.

Experimental Examination of Diode Features in a High-Power Magnetron with a Transparent Cathode

A Magnetron is a high efficiency microwave source, although the energy conversion efficiency of a pulsedpower magnetron with a relativistic electron beam is less than that of a non-relativistic magnetron. We studied the possibility of increasing the energy conversion efficiency of a high-power magnetron using a transparent cathode. The conversion efficiency is controlled by the resonance efficiency between the electron beam and microwave oscillation, and initial rise time of the oscillation. In particular, the initial rise time of interaction with the pulsed-power generator is important. The transparent cathode can lower start-up times and enhance the oscillation efficiency. It consists of independent cathode strips, each of which produces an azimuthal magnetic field. The radial drift velocity of electrons emitted from this cathode is accelerated more than that of electrons emitted from a normal cathode. In particle-in-cell electron simulation, the availability of the transparent cathode was indicated. We investigated the experimental effect of the transparent cathode. The experimental setup of the relativistic magnetron is operated with “ETIGO IV,” which is a 400-kV-class repetitive pulsed-power generator. The start-up time of magnetron with the transparent cathode is shorter than that with a traditional cathode. We expect that the transparent cathode method will be advantageous over the current method. c

Experimental and Simulation Studies of New Configuration of Virtual Cathode Oscillator

A new configuration of a virtual cathode oscillator (VCO) has been studied for high-power microwave generation. In this VCO configuration, a resonant cavity is used to enhance the beam-field interaction in order to improve the microwave efficiency. Experiments were carried out on a repetitive pulsed power generator "ETIGO-IV" (400 kV, 13 kA, 120 ns, 1 Hz). The output microwaves are diagnosed for peak power and dominant mode by using horn antennas and E-field probes. The microwave frequency is obtained by fast-Fourier transformation of the signal recorded by a high-speed digital oscilloscope. The initial experimental results obtained by E-field probes have indicated a beam-to-microwave conversion efficiency of /spl sim/10%. In addition, three-dimensional particle-in-cell simulations were carried out by using simulation code "MAGIC". Simulation results are compared with experimental results to examine the effect of the cavity and possible ways of further improvement of microwave efficiency.

Compact Pulsed Power Generators for Industrial Applications

Various repetitive pulsed power generators have been developed for different applications. Semiconductor switches have greatly extended the scales of pulsed power parameters, especially in repetition rate and lifetime. They have also enabled new areas of pulsed power applications, such as accelerators, flue-gas treatment, and gas lasers.

Development of Pulsed Power Technology and Its Wide Applications

For the wide applications of pulsed power technology, highly repetitive pulsed power generators have been recently developed by use of semiconductor switches. Two examples of recent topics will be introduced. One is a combination of an inductive energy storage and semiconductor opening switch. It produces a sharp voltage spike, which is followed by capacitor discharge with long pulse width. It will be used for excimer laser excitation. Another is stacked MOS-FETs, which can be used in the power supply for the accelerators. Various applications of pulsed electromagnetic energy will be expected using highly rep-rated pulsed power generators.

Repetitive pulsed-power generator "ETIGO-IV"

ETIGO-IV, a new repetitive pulsed-power generator, has been developed. It is capable of delivering, to a matched load, an output pulse of 400 kV in peak voltage, 13 kA in peak current, and 120 ns in pulse length, at the repetition rate of 1 Hz. It is aimed at applications to material development, pulsed ion-beam acceleration, and high-power microwave generation. This paper reports the design details and operation results of ETIGO-IV, as well as the initial experimental results on electron beam generation.