Microwave generation from betatron oscillation of slow electron beam in DC cross-fields configuration

Abstract

A high-efficiency mechanism of microwave (MW) generation from slow electron beam (e-beam) is investigated in details. Space-inhomogeneous density profile of the e-beam enables its current vortex profile ∇ × j easy to be modified significantly by external fields. Suitable DC cross-fields configuration can modify time behavior of the ∇ × j of an e-beam from monotonically-varying to oscillatory. Under available not-too-severe values of beam peak density and beam drifting velocity, such a time-oscillatory current vortex can be tuned to have a narrow-spectrum around a desired central frequency within a broad range from MHz to Thz. The mechanism is applicable to slow non-relativistic e-beam and hence does not need bulky cooling component and high-voltage component. This favors the whole vacuum electron devices (VEDs) to be compact enough without at the cost of lower output power.