An investigation of internal ion number density and electron temperature profiles in a laboratory-model Hall thruster
Experiments have been conducted at the University of Michigan Plasmadynamics and Electric Propulsion Laboratory (PEPL) to investigate the acceleration and ionization mechanisms in the P5 laboratory-model Hall thruster. A cylindrical, double Langmuir probe was used to measure electron temperature and ion number density in the discharge chamber of the PS. Probe residence times inside the thruster, and hence thruster perturbation, were minimized by use of PEPL's High-Speed Axial Reciprocating Probe (HARP) system. Discharge voltage for this experiment was fixed at 300 V and two discharge current settings were considered: 5.4 A (1.6 kW) and 10 A (3 kW). Axial profiles of temperature and number density at multiple radial positions spanning the width of the discharge channel are presented for the two cases along with previously measured profiles of the radial magnetic field and plasma potential. At 1.6 kW, the number density exhibited a dual-peak axial profile indicating two regions of ionization. The maximum temperature and number density was approximately 38 eV and 2.1×l018 m-3, respectively. This structure essentially disappeared at 3 kW, with a single number density peak of 2.8el018. Electron temperature reached a maximum of 32 eV at roughly the same axial location. © 2000 by James M. Haas vPublished by the American Institute of Aeronautics and Astronautics with permission.
