Millimeter wave generation from a pseudospark-sourced electron beam

Experimental studies of the production and propagation of an electron beam from a multigap pseudospark discharge are presented. From a three-gap pseudospark, a beam up to 680 A was measured at the anode at an applied dc voltage of 23 kV. This beam can propagate downstream as far as 20 cm in a gaseous environment with no guiding magnetic field, which confirms that the transport of the electron beam was based on the neutralization of the space charge of the electron beam due to the ionization of the gas molecules by the beam itself. The beam is of very small size of 1-3 mm in diameter and is ideal to drive high frequency radiation. Higher energy electron beam pulses were generated using a 14-gap pseudospark discharge powered by a cable pulser capable of producing 120 ns duration and 170 kV voltage pulses. The beam measured had a current of up to 110 A. Interactions between the produced beam and a Ka-band Cherenkov maser and a W-band backward wave oscillator slow wave structure were simulated and designed. Millimeter wave pulses were detected from the Cherenkov maser and backward wave oscillator beam-wave interaction experiments.