Effects of Internally Mounted Cathodes on Hall Thruster Plume Properties

The effects of cathode position on the operation and plume properties of an 8-kW Hall thruster are discussed. Thruster operation was investigated at operating conditions ranging from 200 to 500 V of discharge voltage, 10-40 A of discharge current, and 2-8 kW of discharge power, with a cathode positioned either in the traditional externally mounted configuration outside the outer magnetic pole piece or in an internally mounted configuration central to the inner magnetic core. With the external cathode, substantial emission in the visible spectrum that follows magnetic field lines surrounds the exterior pole pieces of the thruster. With the internal cathode, the emission is largely absent while the cathode plume is compressed and elongated in the axial direction by the strong axial magnetic field on the thruster centerline. Discharge current oscillation and ion species fraction measurements were found to be similar for the cathode locations, whereas the operation with the internal cathode was found to favor an improved coupling of the cathode plume with the thruster discharge. Ion current density measurements show that with respect to externally mounted designs, internally mounted cathodes reduce plume divergence and increase the symmetry of the near-field plume. The impacts of internally mounted cathodes on thruster physics and spacecraft integration activities are assessed.

[1]  J. Pelletier,et al.  Work function of sintered lanthanum hexaboride , 1979 .

[2]  B Pote,et al.  Performance of an 8 kW Hall Thruster , 2000 .

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

[4]  Terrance Yee.  Roadrunner, a High-Performance Responsive Space Mission , 2004 .

[5]  D. L. Jacobson,et al.  Work Function Measurement of Lanthanum - Boron Compounds , 1978, IEEE Transactions on Plasma Science.

[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]  N. Fisch,et al.  Effects of segmented electrode in Hall current plasma thrusters , 2001 .

[8]  Justin M. Fox.  Parallelization of particle-in-cell simulation modeling Hall-effect thrusters , 2005 .

[9]  R. Seliger.  E×B Mass‐Separator Design , 1972 .

[10]  P. A. Pincosy,et al.  Directly heated lanthanum hexaboride filaments , 1984 .

[11]  David H. Manzella,et al.  The Performance and Wear Characterization of a High-Power High-Isp NASA Hall Thruster , 2005 .

[12]  Dan M. Goebel,et al.  Cathode Coupling in Hall Thrusters , 2007 .

[13]  Kristina Kathleen Jameson.  Investigation of hollow cathode effects on total thruster efficiency in a 6 kW Hall thruster , 2008 .

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

[15]  Michael Keidar,et al.  EFFECT OF A MAGNETIC FIELD ON THE PLASMA PLUME FROM HALL THRUSTERS , 1999 .

[16]  Edmund Storms,et al.  A study of surface stoichiometry and thermionic emission using LaB6 , 1979 .

[17]  W. Kohl.  Handbook of materials and techniques for vacuum devices , 1967 .

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

[19]  M. Keidar,et al.  On the magnetic mirror effect in Hall thrusters , 2005 .

[20]  David Pidgeon,et al.  Two Years of On-Orbit Performance of SPT-100 Electric Propulsion , 2006 .

[21]  J. Polk,et al.  An Overview of the Nuclear Electric Xenon Ion System (NEXIS) Activity , 2004 .

[22]  Vladimir Kim,et al.  Dual-Mode Operation of Stationary Plasma Thrusters , 2006 .

[23]  Edmund Storms,et al.  Phase relationship, vaporization, and thermodynamic properties of the lanthanum-boron system , 1978 .

[24]  Alec D. Gallimore,et al.  Very-Near-Field Plume Investigation of the Anode Layer Thruster , 2000 .

[25]  H. E. Gallagher,et al.  Poisoning of LaB6 Cathodes , 1969 .

[26]  John R. Anderson,et al.  An Overview of the Results from the 30,000 Hr Life Test of Deep Space 1 Flight Spare Ion Engine , 2004 .

[27]  Dan M. Goebel,et al.  Large-area lanthanum hexaboride electron emitter , 1985 .

[28]  A. Gallimore,et al.  Recent Results From Internal and Very-Near-Field Plasma Diagnostics of a High Specific Impulse Hall Thruster , 2003 .

[29]  A. Fruchtman,et al.  Plasma lens and plume divergence in the Hall thruster , 2006 .

[30]  N. C. Wallace,et al.  BASIC ISSUES IN ELECTRIC PROPULSION TESTING AND THE NEED FOR INTERNATIONAL STANDARDS , 2003 .

[31]  James E. Polk,et al.  Extending hollow cathode life for electric propulsion in long-term missions , 2004 .

[32]  Robert S. Jankovsky,et al.  Laboratory Model 50 kW Hall Thruster , 2002 .

[33]  Robert S. Jankovsky,et al.  High-specific impulse Hall thrusters, part 1: Influence of current density and magnetic field , 2006 .

[34]  Roger M. Myers,et al.  Hall thruster-cathode coupling , 1999 .

[35]  John Steven Snyder,et al.  Evaluation of a 4.5 kW Commercial Hall Thruster System for NASA Science Missions , 2006 .

[36]  Alec D. Gallimore,et al.  Effects of cathode configuration on hall thruster cluster plume properties , 2007 .

[37]  E. Ahedo,et al.  A two-dimensional hybrid model of the Hall thruster discharge , 2006 .

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

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

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

[41]  Christian Carpenter,et al.  Life and Operating Range Extension of the BPT-4000 Qualification Model Hall Thruster , 2006 .

[42]  D. Goebel,et al.  Lanthanum hexaboride hollow cathode for dense plasma production. , 1978, The Review of scientific instruments.

[43]  R. Levi,et al.  Improved ``Impregnated Cathode'' , 1955 .

[44]  I. Katz,et al.  Estimation of Hall Thruster Erosion Using HPHall , 2005 .

[45]  Dan M. Goebel,et al.  LaB6 Hollow Cathodes for Ion and Hall Thrusters , 2005 .

[46]  Alec D. Gallimore,et al.  Characterizing Vacuum Facility Backpressure Effects on the Performance of a Hall Thruster , 2001 .

[47]  James Szabo,et al.  Characterization of a High Specific Impulse Xenon Hall Effect Thruster , 2005 .

[48]  J. L Cronin,et al.  Modern dispenser cathodes , 1981 .

[49]  Hani Kamhawi,et al.  High Current Cathode Development for 50 kW C lass Hall Thrusters , 2005 .