Development Of Nanosecond Pulsed Power

Deposition of diamond-like in a short distance discharge under high pressure isa promising technique in plasma.But it’s poor working stability is a technicalbottleneck. They are to be seen in the following: the glow discharge will extinguishif arc discharge happened,and the maintaining voltage can not make the gasbreakdown after it’s extinction.This paper discusses the characteristics of gasdischarge and draw the conclusion that short distance discharge is working on theright part of Paschen curve,and the the increase of negative resistance with the rise ofreaction pressure is the main reason of technical bottleneck. Aiming at this problem,preionization as a solution has been put forward.A high voltage nanosecond pulse generator has been designed based on therequirements of gas preionization.This paper analyzed the advantages anddisadvantages of electric vacuum device and solid state device which both can formhigh voltage nanosecond pulse generator,studied the properties and work conditionsof avalanche transistors.Then,we decided to design this pulse generator using highvoltage field effect transistor combined with avalanche transistor. This system iscomposed of six parts.Pulse generation,pulse sharpening, pulse driver and mainpulse circuit besides high and low voltage power supply. It has greatly improved thepulse amplitude by using many MOSFETs in series, realized the voltage-sharing ofMOSFETs in series by supplying each one with separate power,realizedmulti-channel high DC outputs by using interleaved flyback topology,greatlyreduced the rising time and falling time of drive pulse by avalanche effect ofavalanche transistors,achieved adjusting output pulse width manually by usingseparate driver for the unseal and off of MOSFETs, promoted falling speed of outputpulse by short-circuiting load. Ultimately, achieve a pulse generator with outputamplitude0~4kV adjustable, falling time of output pulse less than18ns, pulsewidth100ns~1us adjustable. After careful experiments and measurements,we haveobtained a large number of experimental waveform and data, verified the feasibilityof the scheme.Experiment with resistive load found that pulse width jitter is small,power output performance is relatively stable, but the top of pulse has slightoscillation. High voltage nanosecond pulse generator can be used to short distanceglow discharge as preionization equipment.