Forschungsinformationssystem Universität Greifswald

Kahnfeld D*, Duras J, Matthias P, Kemnitz S, Arlinghaus P, Bandelow G, Matyash K, Koch N, Schneider R¹

1 - Institut für Physik / AG Computational Science

The high efficiency multistage plasma-thruster (HEMP-T) represents an ion thruster technology that was developed by Thales Deutschland GmbH beginning in the early 2000s. It features a dielectric-coated discharge channel with an anode at the channel bottom. A magnetic field is applied by periodic permanent magnets (PPMs) that is mostly axially oriented in most channel regions, with radial orientation only at spatially confined magnetic cusps resulting in low particle fluxes towards the dielectric wall. The typical length scales in the description of the HEMP-T plasma range from microscopic over mesoscopic to macroscopic. Microscopic effects are introduced, e.g., by atomic interactions and surface interactions. Mesoscopic scales appear by the gyro radius of particles in the magnetic field and the formation of a transition zone between plasmas and walls on the length scale of some Debye lengths, respectively. Large-scale macroscopic length scales are introduced, e.g., by the plume expansion and interaction with test vessel walls. For a correct description of both thruster and plume plasma, one has to solve a kinetic problem for the whole region of interest, including all significant physical processes. This review offers an overview of modeling strategies and their results for the HEMP thruster. The axisymmetric 2D3v Particle-in-Cell (PIC) simulation method is used to identify the basic physics of the acceleration channel and the near-field plume region. Direct comparison with the observed plasma radiation and angular ion energy distributions, both for stationary and dynamic modes, is also presented. While good qualitative agreement with experimental data is achieved, even better agreement with experiments is necessary to predict thruster performance via numerical models in the future. The limited size of the simulation domain restricts the study of the coupled thruster-plume dynamics, which is an important aspect for the interaction of ion thruster and carrier spacecraft. Improvements in computer technology, the use of hierarchical models and the multigrid method discussed in this review can help overcome these limits and improve the quality of predictive thruster modeling.