Mode coupling and conversion in an electron beam-driven low Q gyrotron

Summary form only given, as follows. Electromagnetic fields are computed self-consistently in an electron beam driven low Q gyrotron. This work improves on earlier studies which did not use the correct of eigenmodes in the expansion of the electromagnetic fields or described the external and ohmic losses in the cavity in a phenomenological way. The oscillator equations describing the amplitude coefficients of the individual eigenmodes are solved in the steady state. The momentum equations describing the particle motion are derived. The oscillator equations and the momentum equations are solved self-consistently to completely specify the amplitudes and phases of the individual cavity eigenmodes, and motion of the particles. An optimization procedure is used to iterate over the solutions and to achieve convergence. Coupling and conversion between various eigenmodes through both the external and ohmic wall losses and the electron beam are demonstrated.