A compact source of sub-GW, subnanosecond pulses

Abstract

The system comprises a nanosecond SOS-generator that charges resonantly a short pulse-forming line (PFL) through a decoupling inductor, one or two pulse-compression stages based on high-pressure gas spark gaps (SG), a matched load and several built-in voltage and current probes. Weighing less than 50 kg, the pulser provides up to 160 kV subnanosecond pulses across a 37.5 /spl Omega/ load at repetition rate of up to 300 Hz. The pulsewidth can be regulated from 2 ns down to 300 ps without depressurizing the SGs. The rise- and fall times are typically 200 ps and 150 ps, respectively. Alternatively, unipolar or bipolar output can be provided. The latter was formed by a synchronous operation of SGs located at the beginning and at the end of a PFL; thus, an active conversion of unipolar to bipolar output was realized. The load peak-to-peak voltage was almost two times as high as the amplitude of the unipolar pulse. Voltage and current measurement means were developed and time-domain calibrated. Current and voltage waveforms probed at different locations of the pulser system, from the SOS-generator to the load, are presented. The experimental results are in fair agreement with PSpice simulations used for the hardware design. In the active converter of bipolar pulses, a virtually identical electrical field stress across the switching SGs was achieved, which alone provided its stable operation.