Major Improvement of Gyrotron Efficiency with Beam Energy Recovery

Abstract

A stable, high efficiency, high power oscillation was performed in a gyrotron with beam energy recovery. By the application of an electron retarding potential, efficiency was enhanced from 30% to 50% at an output power of 610 kW (110 GHz). Numerical analysis indicates that the electrostatically trapped electrons are reaccelerated in the cavity due to electron cyclotron resonance and are swept out to the collector or electron gun. This mechanism avoids electron accumulation in the gyrotron even with the high retarding potential.