Slow Wave Electron Cyclotron Maser Utilizing Periodically Corrugated Waveguide

Slow wave electron cyclotron maser composed of a periodically corrugated waveguide and an axially streaming electron beam is considered. This slow wave electron cyclotron maser can be driven by the electron beam with predominant axial velocity and is distinct from the conventional fast wave electron cyclotron maser, in which an electron beam having an initial perpendicular velocity to magnetic field is required. Normal modes in the cylindrical slow wave system with magnetized electron beam are analyzed by a linear fluid model, taking into account of three dimensional beam perturbations and boundary conditions self-consistently. The axially streaming electron beam is able to interact with periodic electromagnetic normal modes at an anomalous Doppler cyclotron resonance, resulting in slow wave electron cyclotron maser instability. When the frequency of the slow wave electron cyclotron maser instability coincides with that of conventional Cherenkov instability, two instabilities can be combined favorably to generate microwave radiation.