Pseudospark-sourced Electron Beam for Millimeter Wave and Terahertz Radiation Generation

The production and propagation of an electron beam from both a multi-gap and a small-scale single-gap pseudospark discharge are investigated. 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. A Ka-band Cherenkov maser and a W-band backward wave oscillator from the produced beam were simulated and experimentally studied. Millimeter wave pulses were detected successfully from both devices. In an effort to show the effects of scaling down the size of the pseudospark discharge on beam performance, a single-gap 1 mm aperture pseudospark electron beam experiment was conducted, based on which a 206 GHz microklystron was designed and simulated.