Design of a high efficiency C-band 60 W space TWT

Design of a high efficiency C-band 60 W space TWT is presented. In-house developed software packages are used for the design of: (i) electron gun, (ii) PPM focusing system, (iii) helix slow wave structure (SWS), (iv) input and output couplers, (v) Beam-Refocusing Section (BRS), and (vi) Multi-stage Depressed Collector (MDC). Results are presented for the low-convergence electron gun with space-charge balanced flow; helix SWS with sever and double-velocity taper for high interaction efficiency; BRS for improving collector efficiency; and 4-stage depressed collector. The design is optimised at beam voltage 3.0 kV and beam current 75 mA. Computed electronic efficiency is achieved better than 32% and overall efficiency better than 55%.