A slow-wave ECM with axial injection

A continuous electron beam injected axially into a slow wave structure containing a circularly polarized TE wave and a longitudinal magnetostatic field will produce microwaves by maser action. The slow wave structure allows energy to be coupled out of an electron beam with no initial transverse momentum. A narrower spread of energy about the ECM resonance and more efficient high power operation is possible with axial injection. A nonlinear (strong field) analysis of energy coupling of electrons to a slow wave in an electron cyclotron maser is presented. A design of a slow wave ECM microwave amplifier at 10 GHz using a 200 keV axial beam in a 3 kG magnetic field is presented.