A 100 watt high efficiency TWT for space communications

A high efficiency ppm focused, traveling-wave tube, which is capable of producing 100 watts of CW power output at 2.3 GHz for space communication use, is described. The achievement of high overall efficiency is the most important aspect of this program since the dc power to the tube represents a major fraction of the total power available on the spacecraft. The tube has produced an overall efficiency of 45%, including heater power, at power levels between 60 and 100 watts at essentially constant gain. Detailed performance curves will be shown. Efficiency improvement work is continuing and any further results will be reported. The tube is of metal-ceramic construction and is designed to operate under launch environmental and space thermal-vacuum conditions. It is mechanically rugged and has demonstrated very low incidental AM and PM modulation under vibration. Cooling of the tube is by conduction. The overall weight of the encapsulated tube is 3.0 lb.