Field analysis of beam loading and detuning in magnicon deflection cavities

Summary form only given, as follows. Making use of Maxwell´s equations, a first principles analysis of the beam-deflection cavity interaction in a magnicon is presented. For a driven cavity this leads to a dispersion relation wherein the interaction modifies the unloaded Q (beam loading) and the resonance frequency (detuning). In terms of a lumped-parameter equivalent circuit. The interaction corresponds to a complex-valued beam admittance, Y/sub e/, in parallel with the cavity shunt impedance. The response of the gain cavities is modified by the same admittance, Y/sub e/. In a magnicon, Y/sub e/ is a sensitive function of the solenoidal focusing magnetic field, B/sub 0/. In fact, when the relativistic gyrofrequency is twice the RF frequency, Im (Y/sub e/)=0 and the beam does not load the cavity. This provides a convenient means of adjusting the cavity properties in experiments. A detailed description of the variation of the detuning. Instantaneous bandwidth (i.e., loaded Q) and gain with B/sub 0/ is presented. Recent results of the NRL X-band magnicon experiment are examined in the light of the analysis.