A KINETIC-THEORY FOR ELECTRON-CYCLOTRON MASER INTERACTION IN A WAVE-GUIDE - COUPLING BETWEEN A TRANSVERSE ELECTRIC MODE AND A TRANSVERSE MAGNETIC-MODE

A kinetic treatment valid at all harmonic cyclotron frequencies is presented for the electron cyclotron maser interaction between a tenuous annular relativistic electron beam and the transverse electric, TE0n, mode in a cylindrical waveguide. Including all equilibrium guiding center trajectory function effects, an improved dispersion relation valid near and far from resonance is obtained. Adding the transverse magnetic, TM0s, mode, the derived dispersion relation reveals that coupling between the two waveguide modes may be significant. Parameter regimes indicating when coupling may be significant are identified. For weakly relativistic and relativistic beams, a wide range of parameters exists when the operating frequency is near the cutoff of either mode. When far from cutoff, similar conclusions are made. A new, direct transfer mechanism between two empty waveguide modes in the presence of the beam is established. Under appropriate conditions, it is explicitly shown that the inclusion of the TM0n mode can enhance or inhibit the growth rate. © 1990 American Institute of Physics.