Study of Directed Ion Fluxes and Plasma Parameter Distributions in the Jet and Vicinity of a Stationary Plasma Thruster Operated on Krypton

The results of an experimental determination of the spatial structure of accelerated ion flows outflowing from a krypton-fueled laboratory model of the SPT-70V—a new stationary plasma thruster with an acceleration zone with the main potential drop removed from its construction—as well as the plasma parameter distributions in the model jet are presented. The removal of the acceleration zone from the thruster discharge chamber allows a significant reduction in accelerated ion flows onto its walls, reducing their sputtering and increasing the thruster service life. The results of a study of the plasma parameter distributions and directed slow ion flows near the “output plane” of this thruster model are also presented. These ion flows move primarily in the “radial” and “reverse” directions and form a plasma cloud in the space around the operating thruster. These data can be used to estimate the potential impacts of the jet of the thruster being developed based on the SPT-70V prototype on the structural elements and various spacecraft systems. These results were used to estimate the efficiency of ionization and ion acceleration in the discharge of the SPT-70V prototype under study, to reveal the features of directed flows of slow ions moving in the closevicinity of the aforementioned “output plane” of the SPT-70V prototype in radial and reverse directions, and the physical factors determining their formation. In particular, the important role of the spatial distributions of the accelerated ion concentration and the electron temperature in the near-axial part of the jet in the formation of the electric potential distributions and directed flows of charge exchange ions moving near the “output plane” of the SPT-70V prototype in directions close to radial ones is demonstrated. It is also shown that the set of the obtained data indicates the dominant role of charge exchange ions in the formation of directed flows of slow ions in the near zone of the jet and the plasma cloud in the space surrounding the operating thruster.