Angularly-Resolved E×B Probe Spectra in the Plume of a 6-kW Hall Thruster

1+ decreased with increased discharge voltage, having values of 0.92, 0.87, and 0.70 at 150, 300, and 600 V, respectively. The plume-averaged Xe 1+ current fraction also decreased with increased flow rate, having fractions of 0.87, 0.75, and 0.60 at 10, 20, and 30 mg/s, respectively. The increasing fraction of multiply-charged ions with discharge voltage was attributed to the increase in electron temperature. The increasing fraction of multiply-charged ions with anode flow rate was explained by the increasing ratio of Xe 1+ to neutral Xe found by plasma simulations in HPHall. The results were corrected for the loss of main beam ions due to charge-exchange collisions between the thruster exit and probe location. The correction method performed well, producing plume-averaged correction factors that were within 0.5% of each other with the probe positioned at 8, 10, and 12 thruster diameters downstream. The correction due to charge-exchange collisions was on the order of 1-5%, depending on operating condition, exceeding the errors introduced by other parameters used in performance models. The plume-averaged correction for multiply-charged ions deviated from the discharge channel centerline value by approximately 1.5% over a range of discharge powers from 1 to 10 kW, with the maximum deviation of 5% occurring at the 600 V, 10 mg/s condition. The results indicate that a single measurement of the local ion current fractions near discharge channel centerline is sufficient to accurately gauge the overall correction for multiply-charged ion species. While this is true for studies that are concerned with the behavior of the thruster over large throttling ranges, plume-averaged quantities are likely to be a necessity for studies focused on fine changes in thruster performance.

[1]  Alec D. Gallimore,et al.  Method for analyzing E×B probe spectra from Hall thruster plumes , 2008 .

[2]  Mitchell L. R. Walker,et al.  Effects of facility backpressure on the performance and plume of a Hall thruster. , 2005 .

[3]  A. Gallimore,et al.  High-Specific Impulse Hall Thrusters, Part 2: Efficiency Analysis , 2006 .

[4]  A. Gallimore,et al.  Plume Study of a 1.35-kW SPT-100 Using an ExB Probe , 2002 .

[5]  Dan M. Goebel,et al.  BPT-4000 Hall Thruster Discharge Chamber Erosion Model Comparison with Qualification Life Test Data , 2007 .

[6]  Sang-Wook Kim,et al.  Experimental investigations of plasma parameters and species-dependent ion energy distribution in the plasma exhaust plume of a Hall thruster. , 1999 .

[7]  R. Hofer,et al.  Development and characterization of high -efficiency, high -specific impulse xenon Hall thrusters. , 2004 .

[8]  Jared M. Ekholm,et al.  E x B Measurements of a 200 W Xenon Hall Thruster , 2005 .

[9]  I. Katz,et al.  Ion Current in Hall Thrusters , 2008, IEEE Transactions on Plasma Science.

[10]  V. Kim,et al.  Local Plasma Parameter Measurements by Nearwall Probes Inside the SPT Accelerating Channel Under Thruster Operation with Kr , 2002 .

[11]  Alec D. Gallimore,et al.  Ion species fractions in the far-field plume of a high-specific impulse Hall thruster , 2003 .

[12]  Rohit Shastry,et al.  Method for analyzing E x B probe spectra from Hall thruster plumes. , 2009, The Review of scientific instruments.

[13]  I. Mikellides,et al.  Efficacy of Electron Mobility Models in Hybrid-PIC Hall Thruster Simulations , 2008 .

[14]  Alec D. Gallimore,et al.  Effect of Backpressure on Ion Current Density Measurements in Hall Thruster Plumes , 2005 .

[15]  A. Gallimore,et al.  Plasma Potential Measurements in the Discharge Channel of a 6-kW Hall Thruster , 2008 .

[16]  C. W. Larson,et al.  Thrust Efficiency, Energy Efficiency, and the Role of VDF in Hall Thruster Performance Analysis (Postprint) , 2007 .

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

[18]  Denis Estublier,et al.  The Smart-1 Electric Propulsion Subsystem , 2003 .

[19]  J. Dymond,et al.  The Virial Coefficients of Pure Gases and Mixtures: A Critical Compilation , 1979 .

[20]  Alec D. Gallimore,et al.  Plume study of a 1.35 kW SPT-100 using an E x B probe , 1999 .

[21]  Yevgeny Raitses,et al.  Temperature gradient in Hall thrusters , 2003 .

[22]  A. Gallimore,et al.  Considerations on the role of the Hall current in a laboratory-model thruster , 2001 .