A kilowatt CW traveling-wave amplifier at 55 Gc

A high-power millimeter-wave traveling-wave amplifier tube is described, which delivers in excess of one kilowatt of CW output power at 55 Gc. The tube features a severed construction to give stability when operating into highly reflective loads. It has a high gain of the order of 25 db. The input end of the output slow-wave section is brought out at the sever to an external port. Thus, it is possible to monitor reflected power and dissipate it in an external load. Oversize waveguide for handling high power is employed at both ends of the output section. An efficiency of 35% is obtained by using a liquid-cooled, depressed collector. Beam area compression is 100 to 1 with a cathode potential of 25 KV and perveance of . Careful gun design and the microinch tolerances of the small coupled-cavity interaction structure make possible the transmission under full rf drive of 98% of the 10 kilowatt beam through a .033 inch diameter beam hole. Focusing field is less than 4 kilogauss. Kilowatt-range tubes are shown to be possible at millimeter-wave frequencies.