A CW 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 in the rapid sintering of high-strength ceramic materials and other heating processes. Millimeter-wave radiation is expected to heat samples much more uniformly and rapidly than conventional furnaces, resulting in improved material properties. 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. The quasioptical resonator comprises two mirrors 6.9 and 13.5 cm in diameter separated by 70 cm with 3% diffractive output coupling at 85 GHz. Cold tests of the asymmetric quasioptical resonator are being performed to measure the quality factor (Q) and variation of Q with mirror alignment. Initial testing of the gyrotron involves pulsed measurements of output power, efficiency, electron pitch angle, mode spectrum, and output radiation pattern. This tunable quasioptical gyrotron complements existing material processing experiments at 2.45 and 35 GHz.