ELECTRON-GUN AND COLLECTOR DESIGN FOR 94-GHZ GYRO-AMPLIFIERS

This paper presents the electrical design of a magnetron injection gun and collector for high peak and average power TE01 W-band gyro-amplif iers, The magnetron injection gun design employs an optimized double-a node geometry and a cathode angle of 50 degrees to achieve superior be am optics that are relatively insensitive to electrode misalignments a nd field errors. A transverse relative velocity spread of 1.6% at a ve locity ratio of 1.5 is obtained in simulations for a 6-A 65-kV beam. C athode edge emission was modeled, found to produce a major effect on v elocity spread, and will be eliminated by nonemissive cylinders affixe d to the cathode. The collector, which also serves as the output waveg uide, is designed to minimize the required collector length while avoi ding eccessive power loading on the collector surface. An average powe r density of less than 640 W/cm(2) on a 3.25-cm-diameter collector is achieved for 91-kW average beam power. Both the gun and collector are currently under construction.