Improvement of optical diagnostic methods for a xenon operating thruster plasma

Improvement of contemporary plasma optical diagnostic technique for xenon Hall effect based thrusters is considered. This improvement has become possible after critical revision of collisional radiative model for the thruster plasma. In particular, three important processes have been included into the collisional radiative model: excitation of the xenon emissions in collisions between xenon ions and atoms; step-wise excitation of xenon atoms through metastable states; pressure dependence of the apparent excitation cross-sections. Effect of these processes on the results of measurements is discussed and illustrated on particular examples. Application of the improved method for measurements of electron temperature and ion number density distribution in the near field of the D-55 thruster plume is discussed. Also presented is advanced method for determination of relative content of impurity atoms sputtered from the thruster body. Results of measurements are presented in comparison with probe and other independent measurements where possible.