The Cyclotron Auto-Resonance Maser (CARM) is under investigation at the US Naval Research Laboratory as an efficient source of high power millimeter-wave and submillimeter-wave radiation for applications such as plasma heating, advanced rf accelerators, and space-based radars. A short-pulse 100 GHz CARM oscillator experiment based on a 600 kV, 200 A, 50 ns electron beam is under way. The mode selective, high-Q waveguide cavity with rippled-wall Bragg reflectors is designed to operate in the TE61 mode. A novel cold cathode diode is used to produce a high quality (Δυz/υz ≤ 3%) annular beam with a momentum pitch ratio of 0.6. The cathode features nonemitting focussing electrodes and an annular velvet emitter. The main objective of the experiment is to demonstrate high efficiency (∼ 20%) at a power of approximately 20 MW. In addition, a long pulse, 250 GHz, CARM oscillator experiment based on a 500 kV, 100 A, 1 μs MIG-type thermionic cathode electron gun is planned. The design of these experiments and the optimization of CARM oscillator efficiency are discussed.
ASJC Scopus subject areas
- Nuclear and High Energy Physics