A cyclotron autoresonance maser (CARM) oscillator experiment is reported, using a 600keV 200 A electron beam and a whispering-gallery-mode rippled-wall Bragg cavity. This device was designed to produce tens of megawatts of radiation at 100GHz from a CARM interaction, but instead produced only moderate powers (tens of kilowatts) in fundamental gyrotron modes near 35 GHZ, in third-harmonic gyro-BWO modes and possibly third-harmonic gyrotron modes, at frequencies near the expected CARM frequency, with no discernable CARM radiation. The lack of observable CARM radiation is attributed to excessive ripple on the voltage waveform and to mode competition. Calculations of the spectrum and growth rate of the backward-wave oscillations are consistent with the experimental observation.
ASJC Scopus subject areas
- Electrical and Electronic Engineering