Resonant Enhancement of Radiation from a Backward Wave Oscillator Utilizing Large Diameter Corrugated Metal Structure

Abstract

An experiment on a backward wave oscillator (BWO) utilizing a largediameter corrugated metal wall slow wave structure (SWS) has beenpresented. Measurements are made above and below the starting beamenergy for conventional BWO operation. For the latter case, an excitednoise-level backward wave at 20 GHz (TM₀₁ mode) is coupled at theends of the SWS to a forward anomalous Doppler shifted electroncyclotron (EC) beam mode which amplifies the original oscillation byan amount of 50 dB. Resultant microwave output powers of 200 kW with4.5 magnetic field for an electron beam with energy 35 keV. Unlike the well-known fast wave devices, our slow wave EC device is simple to operate utilizing an electron beam with dominant parallel velocity in a uniform magnetic field.