Current capabilities of a low inductance Marx generator for driving a high power microwave source

The electrical characteristics and current capabilities of a low inductance Marx generator used to drive a high power microwave (HPM) source are described. The operating frequency of many HPM sources is dependent upon various characteristics of the input voltage pulse from the pulsed power generator. Texas Tech University has developed an 8 stage, 80 J Marx generator used to drive HPM sources at repetition rates up to 500 Hz. The Marx generator is constructed using pulse forming networks rather than discrete capacitors. Experimental efforts have shown stable frequency operation of a virtual cathode oscillator (Vircator) source using a low energy, PFN Marx. Efforts were taken to reduce parasitic inductance of the PFN Marx resulting in a voltage pulse with a risetime less than 25ns with 50ns FWHM. Additionally, efforts were taken to improve impedance matching between the PFN Marx and the vircator load. This article presents experimental results of an 80 J Marx at voltages ranging from 150 kV to 250 kV operating in burst mode. Voltage and current waveforms from the Marx are shown as well as some typical results of compact sealed tube vircator operation.