The effect of velocity spread of pseudospark-sourced electron beam to Y-band extended interaction oscillator

Abstract

Extended interaction oscillator (EIO) operation in the terahertz range puts greater demand on the current density and brightness of an electron beam. The pseudospark (PS)-sourced electron beam is a good candidate for driving such high frequency EIOs as it has a very high combined beam current density and brightness. However, the PS-sourced electron beam can have an inherent velocity spread unless some form of post acceleration is used. Before a new EIO device in the Y-band (220 GHz–325 GHz) based on a PS-sourced electron beam can be realized, it is first necessary to analyze the influence of the beam velocity spread on performance. This paper presents the numerical studies of the EIO performance with the inclusion of the beam velocity spread. It was found that the Y-band EIO circuit can operate in a relatively wide velocity spread range when a high beam current density is used. For an electron beam current density of 1 kA/cm2, the output power is not less than 0.9 times of the power obtained with an electron beam with no velocity spread when the velocity spread is within the range of 0%–15%. We also present our latest results that demonstrate the successful design and optimization of a Y-band EIO driven by a 36 kV, 255 mA (800 A/cm2) PS-sourced electron beam. A peak power over 1.67 kW at 283.7 GHz was achieved using an electron beam, which can be generated by PS discharge, with a velocity spread of 12.5%.