Influence of magnetic field and discharge voltage on the acceleration layer features in a Hall effect thruster

The axial velocity of singly charged xenon ion is determined by means of laser induced fluorescence spectroscopy at the exhaust of a PPS 100-LM Hall effect thruster by analyzing the Doppler shifted spectral profile of the 834.72 nm Xe+ ion line. Measurements are carried out both inside and outside the thruster channel. Ion velocity distribution functions (VDF) are used to compute the ion accelerating potential. It is shown that such a potential can in fact be defined in several ways due to the overlap between the ionization and acceleration layers, which translates into broad VDF. The PPS 100-LM thruster is operated under an applied voltage ranging from 100 to 300 V and a magnetic field produced by coils whose current is varied from 2.5 to 5.5 A. The broad range of working conditions allows one to determine the influence of these two parameters on the ion dynamics. Finally, the experimental results are used to confirm the outcomes of a 2D kinetic model.