Kinetic description of the influence of electron-beam misalignment on the performance of a coaxial-cavity gyrotron

Abstract

Based on the gyrokinetics of free-electron masers, the influence of the electron-beam misalignment on the energy-transfer rate and starting current of a coaxial cavity gyrotron oscillator is studied. As a practical example, a numerical analysis is given to the 1.5 MW/140 GHz coaxial-cavity gyrotron that is being constructed at the Forschungszentrum Karlsruhe (FZK) [M. Thumm, Fusion Eng. Design 30, 139 (1995)]. Results show that the electron-beam misalignment will decrease the energy-transfer rate and increase the starting current, and the dependence of the output power on the magnetic field may become more sensitive due to a poor alignment of the electron-beam.