Theoretical explanation and experimental observation of effective cyclotron coupling of traveling and near-cutoff modes on a phase-synchronized electron beam

For a Cyclotron Resonance Maser (CRM! with a helical axis-encircling electr on beam, the possibility of a strong interaction between cutoff (gyrotron) and traveling Doppler-up-shifted Cyclotron Autoresonance Maser (CARM) modes , which are in resonance with the electrons at the same frequency, is demon strated. This effect can be used in a CRM-oscillator of a new type, where t he feedback and the mode selectivity for the operating traveling mode are p rovided due to the excitation of the cutoff mode. According to both the the ory and experiment, such a scheme can provide an effective excitation of th e traveling mode with negligibly low losses associated with the cutoff mode . (C) 2000 Elsevier Science B.V. All rights reserved.