Carbon-fiber emitter in a cyclotron-resonance maser experiment

A compact cyclotron-resonance oscillator which employs a carbon-fiber electron-gun is presented in this paper. The maser oscillates at ∼3 GHz frequency near the electron cyclotron-resonance. The 2mm diameter carbon-fiber cathode emits ∼1 A current at ∼1 kV voltage. The electron beam tends to be unstable. Clear bursts of RF oscillations are observed in this experiment.