34 GHz Second-Harmonic Peniotron Experiment

Summary form only given. The peniotron has previously demonstrated very high (up to 75%) conversion efficiencies (T. Ishihara et al., 1999). However, high output powers with high device efficiency at mm-wave frequencies have not been reported. The UC Davis peniotron is designed to demonstrate high device efficiency at 100 kW power levels. The device operates in the second cyclotron harmonic at 34 GHz as a first step toward higher harmonics and frequencies. Design parameters for the device have been previously reported (D.B. McDermott et al., 2000) and large-signal codes predict output power and device efficiency of 125 kW and 47% respectively. The device utilizes a second-harmonic interaction with the fundamental mode in a four-vane slotted (magnetron-like) cavity. The interaction B-field is 6.5 kG which is achieved with conventional coils. Previously, the magnet was tested and its performance verified (L.J., Dressman et al., 2006). An adjustable pole piece allows the interaction B-field to be tapered. Key to the device is the axis-encircling electron beam produced by a Northrop Grumman cusp electron gun (D.A. Gallagher, 2000). The original design called for a 70 kV, 3.5 A beam. Output power is extracted from four ports which directly couple to each of the cavity slots. Initial testing has produced output power at 34 GHz with peak power levels in the range of a few kilowatts while operating at a reduced beam voltage of approximately 40 kV. Future efforts will concentrate on operation at full power and optimization of the magnetic fields.