Production of high power microwaves with a compact Marx generator

Summary form only given. A compact pulsed power system has been built at CESTA to drive low impedance high power microwave (HPM) sources. This system stores 10 kJ and is capable of delivering a current up to 50 kA at 800 kV to a matched load. The rise time of the current is less than 100 ns. We have coupled the Marx generator with a vircator tube that produces HPM in S-band. In this paper we describe the experimental setup, the associated HPM measurements and the results obtained with the simulation code MAGIC. The utilization of a fast oscilloscope (3 GHz bandwidth) enables us to examine in detail the frequency spectrum of the Vircator radiation. The spectra are time resolved with a window-shifted finite Fourier transform method. Standard calibrated horns are placed at appropriate locations in the far-field radiation pattern. Precise knowledge of the attenuation of the diagnostic lines associated with the variation with frequency of the radiation pattern allows us to measure the radiated power. The low efficiency generally observed in a basic Vircator configuration can be improved by placing a frequency-matched cavity downstream from the anode. The corresponding TM01 mode can then be made preponderant by a correct choice of the length and radius of the beam pipe that precedes the large conical radiating horn.