Development of an 800 W Ka-band, ring-bar TWT

A detailed description of the ring-bar design is presented along with the RF performance data on one of the development tubes. Performance tests have demonstrated in excess of 700 W at 31 GHz. The tube features periodic permanent magnet (PPM) focusing, conduction cooling, and a nonintercepting gridded gun design. Helix derived circuits such as the ring-bar circuit offer several advantages over traditional helix circuits, including higher power levels, higher efficiencies, and improved thermal capabilities while maintaining equivalent costs. This development program is directed toward a 800-W tube operating at 35 GHz, at duties up to 30%.<>