A unique all solid-state pulsed power system has been tested at the Naval Research Laboratory that produced 200 kV, 4.5 kA, and 300 ns pulses, continuously for more than 11,500,000 shots into a resistive load at a repetition rate of 10 pps. The Marx has an efficiency of 80% based on calorimetric measurements. This pulser is used to evaluate components and advance solid state designs for a next generation solid-state pulsed power system to drive an electron beam pumped KrF laser system for inertial fusion energy. The solid state pulser, designed and constructed by PLEX LLC, consists of a 12 stage Marx, coupled with a 3rd harmonic stage to sharpen the Marx output waveforms, a main magnetic switch, a compact pulse forming line used as a transit time isolator, and a resistive load. Each Marx stage uses an APP Model S33A compact high voltage switch that consists of 12 series connected thyristors. A life test on individual thyristors showed operation of >; 300 M shots at 20 Hz without failure.

A durable gigawatt class solid state pulsed power system

High-performance trigger generators with high amplitude, fast rise time, low jitter are essential for large-scaled pulsed-power systems. Most of the trigger generators are also tiny multistage pulsed-power systems with complicated structures. In this paper, a high-performance trigger generator was proposed by combining the advantages of low-jitter semiconductor switch and high-power gas switch. An avalanche transistor Marx circuit was developed. It was used to trigger a two-stage Marx generator based on trigatron switch. The output characteristics of the Marx circuit based on avalanche transistors and the two-stage Marx generator were studied. The experimental results show that a subnanosecond jitter, nanosecond rise time, high-voltage trigger generator can be achieved by triggering trigatron switch with an avalanche transistor circuit.

A Subnanosecond Jitter Trigger Generator Utilizing Trigatron Switch and Avalanche Transistor Circuit

The avalanche transistor-based Marx circuit has great advantages in generating high-voltage nanosecond pulses. The introduction of auxiliary triggering topology (ATT) can reduce the damage probability of transistors in M × N -stage Marx bank circuits (MBCs). However, as the number of modified stages increases, the output voltage drops significantly, which makes it not achievable to adopt ATT at each stage. The transistors in nonmodified stages still have a certain failure rate when operating at a high repetition rate. Moreover, the previous ATT is only applicable in the negative polarity MBC. In this article, an improved ATT is proposed to solve the above problems. First, its operating principle is analyzed, and the feasibility of its application in both negative and positive MBCs is verified by simulations. Then, the effects of the improved ATT on M × N -stage MBCs are experimentally studied, and the results show that the improved ATT can be used in all stages of MBC without reducing the output voltage. It can also reduce the minimum operating voltage of transistors and widen the regulating range of output voltage. In addition, it can improve the synchronous conduction of parallel-connected transistors. Finally, two nanosecond pulse generators with positive and negative polarity, respectively, are developed and used to drive the atmospheric pressure plasma jet. The amplitude of output voltage can be adjusted in the range of 5–10 kV, measuring at the open end of a coaxial cable with 75 Ω impedance, and the maximum repetition rate is up to 7 kHz.

Improved Auxiliary Triggering Topology for High-Power Nanosecond Pulse Generators Based on Avalanche Transistors

Marx bank pulse circuit based on avalanche transistors can generate high amplitude, high-repetition-rate and low-jitter ultra-wideband pulses The rising edge of the pulse is determined mainly by the performance of avalanche transistors The amplitude of the pulse can be adjusted by changing the number of stage and the value of charging capacitors In this paper, A 25 stages Marx bank pulse circuit is designed and tested, In order to reduce the jitter of the output pulses, an optimized driver circuit is designed and the charging resistors and capacitors are tuned to achieve a higher amplitude Finally, 27 kV peak voltage of the output pulse is obtained, the FWHM is 1 ns, the maximum repetition rate is 10 kHz

High power pulse generator based on avalanche transistor Marx circuit

Bipolar junction transistors (BJTs) have been widely studied and used in nanosecond high-voltage pulse generators due to the advantages of fast switching speed and high repetitive frequency. Usually the Marx-type circuit is used to raise the peak value of output pulses. In this paper, a traditional BJT-Marx circuit using charging resistors is analyzed theoretically and experimentally. Based on the results, the structure of a circuit is changed to decrease the isolation voltage across the resistors, and diodes are used to replace charging resistors to block capacitors discharging to resistors. Experimental results showed that the three Marx generators proposed in this paper output pulses with higher voltage amplitude, and the last improved circuit outputs pulses with faster fall times at a higher efficiency.

Theoretical Analysis and Improvement on Pulse Generator Using BJTs as Switches

We have developed a small sized all solid-state pulsed power generator for industrial applications and biomedical applications such as an ozonizer and a cell treatment. In this paper, a novel 19 stages Miniature Marx Generator using bipolar junction transistors (BJTs) to produce high voltage and low energy pulses with nano-seconds pulse rise time is described. This pulsed power generator is consisted of a Cockroft-Walton circuit and a Miniature Marx circuit. The Cockroft-Walton circuit charges all capacitors and the charging voltage is about 300 V. The Miniature Marx circuit is consisted of resistors, capacitors, and BJTs as extreme high speed closing switches using avalanche breakdown phenomena. Another set of BJTs are placed in parallel with the load to turning off a load current. The size of Miniature Marx circuit is 72 mm × 95 mm. The pulsed power generator developed here has an output voltage of about −5.2 kV and a pulse duration of 7 ns. The charging energy of primary capacitors is the milli-Joule regime.

Development of Miniature Marx Generator using BJT

Atmospheric pressure micro plasma jets have been developed for industrial and medical applications, such as the dental treatment, inner surface treatment of capillaries, stimuli of microorganisms and local cleaning of semiconductor devices. An advantage of atmospheric pressure air micro plasma jets is a capability to irradiate plasma to a narrow area, and also is not to require vacuum devices with the ultra-portable and miniaturized size. In this paper, the pulsed power generated micro plasma jets are compared with the DC generated micro plasma jets in gases of air, N2 and O2. Especially, the spectroscopic observation of micro plasma jets is reported comparing two kinds of plasma jets. In the case using the DC power supply, the N2 second positive band, the N2 first positive band, the O radical peak at 777 nm, and NO band of ~300 nm are observed. In the case using the pulsed power source, lines of wavelength between 400 and 600 nm were observed.

Makoto Inokuchi

Papers

Development of Miniature Marx Generator using BJT

Spectroscopic observation of micro plasma jets generated by pulsed power

Characteristics of microplasma jet using air flow and pulsed power