Wave propagation and absorption in a Helicon plasma thruster and its plume

Abstract

A two-dimensional, full-wave, frequency domain, cold plasma model is used to study electromagnetic power propagation and absorption in a helicon plasma thruster, including its far plume region and surrounding space. Re- sults show that a fraction of power is absorbed in the plume region, and that power deposition in the source is essentially unperturbed by the simulation domain size, the presence of metallic obstacles, or the plasma den- sity in the environment. An electron-cyclotron reso- nance (ECR) surface always exists downstream that ef- fectively prevents radiation to the space beyond along the plume. In the presence of an overdense environmen- tal plasma, like the one expected in a vacuum cham- ber, elds are fully evanescent beyond this transition, and vacuum chamber boundary conditions a ect but lit- tle the waveelds before this surface. In the absence of an environmental plasma, a double wave regime transition exists at the interface between the plasma and vacuum that hinders accurate numerical simulation in the plume region.