Mixed slow-wave operation of a wide-band dielectric gyrotron

Abstract

The bandwidth broadening effect of mixing two slow-wave modes in a dielectric loaded gyrotron is investigated for a small axial momentum spread. The usual intermediate wavelength mode (IWM) integrates with the short wavelength mode (SWM) by reducing the electron beam radius, and creates a mixed slow wave. The resulting bandwidth for the mixed mode gyrotron becomes at least twice broader than that for the pure IWM at the small velocity spread (≲1%) with a substantial contribution of the SWM. Moreover, the presence of the SWM reduces considerably the troublesome heat dissipation in the dielectric layer. Therefore, the mixed mode operation can allow up to several times more power than the usual IWM mode operation.