Generation of millimetre waves from a pseudospark discharge electron beam

• Main Author: Bowes, David
• Published: University of Strathclyde 2013
• Subjects: 530
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.665214

A backward wave oscillator (BWO) powered by a 4-gap pseudospark (PS) discharge-generated electron beam has been designed, modelled and constructed, and has been found to generate 2.7 W of RF power at a frequency of 199 GHz. This work presents numerical simulations and experimental results of this work, as well as the techniques, apparatus and diagnostics involved in the manufacture and testing of this device. The physics underlying both the BWO and the PS discharge, a low-pressure plasma phenomenon of high peak current, fast rise time and capable of generating a high quality, high brightness and high current density self-focussing electron beam, will be examined. Also two other devices will be explored: a BWO operating at 67 GHz and a multi-cavity klystron, a form of linear beam amplifier, operating at 94 GHz. The operating and bunching mechanisms of the klystron shall be likewise explored, along with the steps taken for the physical construction of such a miniscule and technically demanding device. A detailed exploration of the PS electron beam has been undertaken, with particular focus on the successful generation of electron beams of sub-millimetre radii. A PS discharge has also been applied for the generation of electron beams, successfully resolving a sub-mm diameter object and generating X-ray photons with energies of 15.83 keV when a 46 kV electron beam was directed towards a molybdenum target/witness plate. This is a step towards the development of a pseudospark-based small-point X-ray imaging source.