Mode-primed operation of an 85 GHz quasioptical gyroklystron

The quasioptical gyrotron (QOG) is currently under development at the U.S. Naval Research Laboratory as a high power source of millimeter-wave radiation. A quasioptical gyroklystron configuration has recently been realized by the addition of an open-mirror prebunching resonator driven by an 85 GHz, 1.5 kW extended interaction oscillator (EIO). The experiment is designed to operate at a voltage of 70 kV and beam currents of 5–15 A. The experiment is currently in progress, and results are presented for EIO mode priming and depressed collector operation at powers up to 100 kW. A technique for increasing the efficiency by adjusting the electron beam parameters on the rise of the voltage pulse is also described.