$\hbox{Xe}^{+}$ Ion Transport in the Crossed-Field Discharge of a 5-kW-Class Hall Effect Thruster

The velocity-distribution function (VDF) of metastable Xe+ ions was measured along the channel axis of the 5-kW-class PPSX000 Hall effect thruster by means of laser-induced fluorescence spectroscopy at 834.72 nm for various voltages, magnetic fields, and mass flow rates. Axial-velocity and dispersion profiles are compared to on-axis profiles obtained with the 1.5-kW-class PPS100 thruster. Outcomes of the comparison are threefold: 1) The broadening of the VDF across the region of strong magnetic field is a general feature for Hall thrusters. It originates in the overlap between ionization and acceleration layers. The kinetic-energy dispersion increases with the discharge voltage; it reaches up to 200 eV at 700 V. 2) Most of the acceleration potential is localized outside the thruster channel whatever the thruster size and operating conditions. The electric field moves upstream when the applied voltage is ramped up, i.e., the fraction of potential inside the channel increases with the voltage. On the contrary, the electric field is shifted downstream when the gas flow rate increases. The magnetic field has a little impact on the potential distribution. 3) A nonnegligible amount of very fast (kinetic energy higher than the applied potential) and very slow Xe+ ions are always observed. Such ions may find their origin in space and temporal oscillations of the electric field as suggested by numerical simulations carried out with both kinetic and hybrid models.

[1]  François Rogier,et al.  Determination of the ionization and acceleration zones in a stationary plasma thruster by optical spectroscopy study: Experiments and model , 2001 .

[2]  S. Mazouffre,et al.  Influence of magnetic field and discharge voltage on the acceleration layer features in a Hall effect thruster , 2008 .

[3]  L. Garrigues,et al.  Critical assessment of a two-dimensional hybrid Hall thruster model: Comparisons with experiments , 2004 .

[4]  A. Morozov,et al.  Fundamentals of Stationary Plasma Thruster Theory , 2000 .

[5]  N. Fisch,et al.  Electron-wall Interaction in Hall Thrusters , 2005 .

[6]  M. Cappelli,et al.  Laser-induced fluorescence measurements of velocity within a Hall discharge , 2001 .

[7]  Denis Estublier,et al.  The SMART-1 Electric Propulsion Subsystem around the Moon: In Flight Experience , 2005 .

[8]  J. Adam,et al.  Study of stationary plasma thrusters using two-dimensional fully kinetic simulations , 2004 .

[9]  L. Garrigues,et al.  Role of anomalous electron transport in a stationary plasma thruster simulation , 2003 .

[10]  M. Martinez-Sanchez,et al.  Spacecraft Electric Propulsion—An Overview , 1998 .

[11]  Evolution of the Ion Velocity Distribtuion in the Near Field of the BHT-200-X3 Hall Thruster , 2006 .

[12]  M. Cappelli,et al.  Comparison of hybrid Hall thruster model to experimental measurements , 2006 .

[13]  A. Gallimore,et al.  Internal plasma potential measurements of a Hall thruster using plasma lens focusing , 2006 .

[14]  Alec D. Gallimore,et al.  Ion-Energy Diagnostics in an SPT-100 Plume from Thrust Axis to Backflow , 2004 .

[15]  Robert H. Frisbee,et al.  Advanced Space Propulsion for the 21st Century , 2003 .

[16]  K. Makowski,et al.  Wall material effects in stationary plasma thrusters. II. Near-wall and in-wall conductivity , 2003 .

[17]  M. Dudeck,et al.  Wall material effects in stationary plasma thrusters. I. Parametric studies of an SPT-100 , 2003 .

[18]  R. S. Robinson,et al.  Physics of closed drift thrusters , 1999 .

[19]  E. Ahedo,et al.  Effects of the radial plasma-wall interaction on the Hall thruster discharge , 2003 .