Development of Terahertz backward wave oscillators

Summary form only given. Calabazas Creek Research, Inc.is funded by NASA to develop efficient, light-weight, backward wave oscillators (BWOs) for applications from 300 GHz to 1.5 THz. These devices are needed as local oscillator sources in heterodyne receivers. Above 100 GHz, only BWOs have broad tunability (over 100 GHz) and high output power (∼1 mW); however, existing sources are heavy, consume excessive power, require water cooling, and have poor output mode purity. The technical objectives of the current program are as follows: incorporate a depressed collector to improve the efficiency and eliminate water cooling; improve the electron gun and configuration of the circuit to increase interaction efficiency; improve the output coupling to increase mode purity; and reduce the magnet system size and weight. A solid model of the final BWO configuration is detailed in this paper. The BWO operates in a 1.1 Tesla, flat magnetic field provided by a permanent magnet. The device operates at 3000-6000 V and is predicted to produce 6-8 mW of RF power continuously from 600-700 GHz.