Pulsed testing of a quasioptical gyrotron for materials processing

Summary form only given. The quasioptical gyrotron (QOG) is under development at the Naval Research Laboratory as a high power source of millimeter-wave radiation. Recent experimental results include the production of up to 150 kW output power with 20% efficiency in 13 /spl mu/sec pulses. A new application of the QOG is the processing of ceramics and other non-metallic materials. High power millimeter-wave radiation offers unique capabilities for the application of coatings, sintering, brazing and soldering, and treatment of polymers. The new experiment is designed to produce 4 kW average power from 75-95 GHz using a 20 kV, 1.5 A DC electron beam. Initial pulsed testing has been performed at 20-60 kV cathode voltage, 0-6 A in 13 /spl mu/sec pulses. A pair of capacitive probes in the drift region are used to measure the average pitch ratio (/spl alpha/=/spl upsi//sub /spl perp////spl upsi//sub /spl par//) of the gyrating electron beam. The pitch ratio is varied by adjusting the magnetic field at the gun or the intermediate anode voltage. Measurements indicate that the average /spl alpha/ of the beam is less than simulation values for low cathode voltages.