Design of a 100 GHz CARM (Cyclotron Auto-Resonance Maser) Oscillator Experiment

摘要

The cyclotron auto-resonance maser (CARM) is a promising source of high-power radiation in the 100 GHz to 500 GHz frequency range that may impact the requirements of advanced systems for applications such as those mentioned above. The requirements for guide magnetic-field strength and electron energy in a CARM may be advantageous when compared with competing devices. Compared with a gyrotron, the required magnetic field strength requirement is substantially reduced. The CARM can provide mm and sub-mm radiation in the first electron-cyclotron harmonic using currently available magnet technology. For example, the experiment at the Naval Research Laboratory is designed to produce powers in excess of 10 MW at 100 GHz with a 600 kV beam and a magnetic field of only 25 kG, while a first-harmonic gyrotron operating at 100 GHz with the same beam voltage requires magnetic field of over 70 kG. Compared with a conventional magnetostatic-wiggler FEL, the CARM can reach sub-mm wavelengths with a lower electron-beam voltage. For example, a 500 kV CARM oscillator has the potential for efficient multi-MW operation at wavelengths down to 0.75 mm with a 100 kG superconducting magnet; a 500 kV FEL oscillator with a 3 cm period magnetic-wiggler will produce radiation at 4.5 mm. The CARM can be either an amplifier or an oscillator. An oscillator design removes the need for an input source and input couplers. In addition, amplifier operation requires suppression of backward-wave instabilities. (RH)