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 2-pi 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 approximately 300 MW in X band from a 10 slot HASR system; approximately 500 MW in Ku band from a 20 slot VR system; and about 15 MW in K band from approximately 30 slot systems. The peak efficiency is approximately 15 percent. The radiation characteristics are in reasonably good agreement with the theoretical predictions. The reduced power levels for approximately 30 slot systems are partially attributed to radial mode competition.