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Near Discharge Cathode Assembly Plasma Potential Measurements in a 30-cm NSTAR Type Ion Engine During Beam ExtractionFloating emissive probe plasma potential data are presented over a two-dimensional array of locations in the near Discharge Cathode Assembly (DCA) region of a 30-cm diameter ring-cusp ion thruster. Discharge plasma data are presented with beam extraction at throttling conditions comparable to the NASA TH Levels 8, 12, and 15. The operating conditions of the Extended Life Test (ELT) of the Deep Space One (DS1) flight spare ion engine, where anomalous discharge keeper erosion occurred, were TH 8 and TH 12 consequently they are of specific interest in investigating discharge keeper erosion phenomena. The data do not validate the presence of a potential hill plasma structure downstream of the DCA, which has been proposed as a possible erosion mechanism. The data are comparable in magnitude to data taken by other researchers in ring-cusp electron-bombardment ion thrusters. The plasma potential structures are insensitive to thruster throttling level with a minimum as low as 14 V measured at the DCA exit plane and increasing gradually in the axial direction. A sharp increase in plasma potential to the bulk discharge value of 26 to 28 volts, roughly 10 mm radially from DCA centerline, was observed. Plasma potential measurements indicate a low-potential plume structure that is roughly 20 mm in diameter emanating from the discharge cathode that may be attributed to a free-standing plasma double layer.
Document ID
20060006322
Acquisition Source
Glenn Research Center
Document Type
Contractor Report (CR)
Authors
Herman, Daniel A.
(Michigan Univ. Ann Arbor, MI, United States)
Gallimore, Alec D.
(Michigan Univ. Ann Arbor, MI, United States)
Date Acquired
September 7, 2013
Publication Date
January 1, 2006
Subject Category
Spacecraft Propulsion And Power
Report/Patent Number
E-14743
NASA/CR-2006-213296
AIAA Paper 2004-3958
Report Number: E-14743
Report Number: NASA/CR-2006-213296
Report Number: AIAA Paper 2004-3958
Meeting Information
Meeting: 40th Joint Propulsion Conference and Exhibit
Location: Fort Lauderdale, FL
Country: United States
Start Date: July 11, 2004
End Date: July 14, 2004
Sponsors: American Society of Mechanical Engineers, American Society for Engineering Education, American Inst. of Aeronautics and Astronautics, Society of Automotive Engineers, Inc.
Funding Number(s)
CONTRACT_GRANT: NAG3-2216
CONTRACT_GRANT: NNC04GA36G
WBS: WBS-22-319-20-B2
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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