Ion velocity evolution with channel width, magnetic topology and propellant in a 200 W Hall thruster

Influence of the geometry and magnetic field strength of the thruster on the ion velocity and acceleration pattern is a crucial point for ion engine as it determines to a large extent the performance level. Ion velocity on-axis profiles were studied in a low power permanent magnet Hall thruster for three channel widths, three magnetic magnitudes and two anode mass flow. Ion velocity distribution functions were measured by means of laser induced fluorescence spectroscopy in the near infrared along the channel centerline in the plume near-field. Close examination of ion velocity distribution function reveals new features which could involve charge exchange collisions with the background gas and beams interaction between each side of the channel of the thruster. Xe ion axial velocity is not influenced by the anode mass flow, but strongly affected by the channel width and the magnetic field strength. Maximum velocity is highest for the largest channel and the strongest magnetic field. Change in near-wall conductivity and electron transport in volume through the magnetic barrier are likely to explain this evolution. Study of Kr ion axial velocity revealed features similar to the examination of Xe ion velocity.