Progress in the development of a high power gyroklystron for accelerator applications

Summary form only given. At the University of Maryland, we have been developing high-power coaxial gyroklystrons for several years. Lately, we have been working on the development of a second-harmonic device capable of driving a high gradient linear accelerator recently developed by the Haimson Corporation. This gyroklystron tube operates at 17.136 GHz, and is expected to produce output pulses with power above 60 MW. In the past, the tube´s performance has been quite short of the design criteria. This unfortunate behaviour has been traced to thermal imperfections in the custom-made high current emitter of our electron gun. These imperfections give rise to instabilities in the input cavity of our amplifier tube, which in turn severely limit the operation of the circuit. In order to counteract this problem, we have radically redesigned the input cavity, changing both its geometry and Q factor. The new input cavity has been fabricated and cold-tested. The gyroklystron would undergoes a series of experimental studies, which would takes place after an upgrade of our vacuum system.