High Power Microwave Generation from a Large Orbit Gyrotron

A study of the production of high power microwave radiation from a large orbit gyrotron in azimuthally periodic boundary systems has been conducted. Linear growth rates have been calculated for the 2π modes of magnetron-like hole-and-slot resonator (HASR) and vane resonator (VR) systems using a general growth rate formalism. The experiment involves the interaction of a 2.3 MeV, 1-2 kA, 5 ns rotating electron layer with the HASR and VR structures. Maximum power levels are ~ 300 MW in X band from a 10 slot HASR system; ~ 500 MW in Ku band from a 20 slot VR system; and ~ 15 MW in K band from ~ 30 slot systems. The peak efficiency is ~ 15%. The radiation characteristics are in reasonably good agreement with the theoretical predictions. The reduced power levels for ~ 30 slot systems are partially attributed to radial mode competition.