Abstract
Experimental results are presented from the first free electron maser experiment to use a pseudospark electron source. A pulsed, 70--80 kV, 10 A electron beam of normalized brightness ${10}^{11}\mathrm{A}\mathrm{m}{}^{\ensuremath{-}2}\phantom{\rule{0ex}{0ex}}{\mathrm{rad}}^{\ensuremath{-}2}$ and current density $1\mathrm{kA}\mathrm{cm}{}^{\ensuremath{-}2}$ from a pseudospark electron cathode was used to produce coherent microwave radiation via a Cherenkov interaction between the electron beam and the ${\mathrm{TM}}_{01}$ mode of a 60-cm-long alumina-lined waveguide. A gain of 29 dB was measured with an output power of 2 kW in the frequency range 25.5--28.6 GHz. The experimental results were found to be consistent with numerical simulations of Cherenkov amplification.
Highlights
Free electron masers have been of general interest for over 20 years and discharges have been studied for much longer
The PS discharge offers the possibility of fast, high repetition rate, high power closing switches [3,4], and electron beam sources of high current density
A resonant Cherenkov interaction between this beam and the TM01 mode of an alumina-lined waveguide in the frequency range 25.5–28.6 GHz allowed amplification of low power broadband microwave radiation emitted by the PS discharge and resulted in a measured gain of 29 dB
Summary
Free electron masers have been of general interest for over 20 years and discharges have been studied for much longer. This experiment involved a Cherenkov maser amplifier driven by an electron beam of 10 A, 70–80 kV, diameter 3 mm, and normalized brightness 1011 A m22 rad22 from a PS cathode.
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