A compact, low jitter, fast rise time, gas-switched pulse generator system with high pulse repetition rate capability

Abstract

We present the experimental results of an ongoing research effort focused on the development and refinement of a compact, low jitter, fast rise time, command triggered, high peak power, high pulse repetition rate (PRR), gas-switched pulse generator system. The main component of the system is a gasswitched Marx-like pulse generator module designed for applications including UWB radar, microwave sources, and triggering large scale multi-module pulsed power systems of all types. The pulse generator system, comprised of a single or multiple Marx modules, is command triggered by a single or multiple TTL level pulses generated by a timing and control system implemented using LabVIEW software and a PXI-based hardware system. The TTL trigger pulses fire all solidstate high voltage trigger pulsers that close the first stage switches in the Marx modules using a novel method to reduce jitter. The control system also accepts user input to set the desired output conditions, adjusts the charge voltage of a high voltage capacitor charging power supply, inhibits capacitor charging during firing of the pulse generators, and can control the system in a closedloop fashion to maintain relative timing and output characteristics during timing drifts and changing environmental conditions. The individual Marx stages are compact and stackable and utilize field enhanced spark gap switches. The stage capacitors are charged in parallel through mutually coupled inductors in series with resistors. This charging scheme allows for high PRR operation limited only by the stage switch recovery time and the power of the available capacitor charging power supply. The stage switches are optically coupled to aid in Marx output voltage formation and to minimize system jitter. The Marx generator is housed in a lightweight aluminum pressure vessel and is operated in a low pressure dry air environment. The design exhibits a low inductance which varies depending on the number of stages used. Using a five stage prototype, we have generated output voltages of ~100 kV with a rise time of <4 ns. The output pulse width is variable and is dependent on the value of the Marx stage capacitors used and the load resistance. The pulse generator system has been operated in a burst mode at a PRR in excess of 1 kHz with good output voltage regulation. The total jitter of the Marx generator system, i.e. from the application of the trigger pulse to arrival of the output pulse, was measured and found to be <1 ns. 1227 9781-4244-4065-8/09/$25.00 ©2009 IEEE