Operation of a high-harmonic gyrofrequency multiplier

The operation of a sixth-harmonic gyrofrequency multiplier is described. The initial experimental results produced 3.5 kW of 17.23 GHz radiation from a 260 keV, 0.3 A, =v/v=4.8 axis-encircling electron beam in a near uniform magnetic field. The output cavity conversion efficiency was measured at 4.5% compared to the predicted value of 8% from a nonlinear simulation code. The design for a higher power, higher efficiency device utilizing magnetic tapering is also presented.