Two-dimensional plasma-wave interaction in an helicon plasma thruster with magnetic nozzle

An axisymmetric, finite difference frequency domain model is used to study the wave propagation and power absorption in a helicon plasma thruster operating inside a laboratory vacuum chamber. The magnetic field is not purely axial and the plasma beam is cylindrical in the source and divergent in the magnetic nozzle. The influence of the magnetic field strength, plasma density, electron collision frequency and geometry on the wavefields and the power absorption maps is investigated, showing different power deposition patterns. The electromagnetic radiation is not confined to the source region but propagates into the nozzle divergent region, and indeed the power absorption there is not negligible. For the impedance at the antenna, the reactance is rather constant but the resistance is very dependent on operation parameters; optimal parameter values maximizing the resistance are found.