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Background Pressure Effects on Ion Velocity Distributions in an SPT-100 Hall Thruster

MacDonald-Tenenbaum, Natalia and Pratt, Quinn and Nakles, Michael and Pilgram, Nickolas and Holmes, Michael and Hargus, William, Jr. (2019) Background Pressure Effects on Ion Velocity Distributions in an SPT-100 Hall Thruster. Journal of Propulsion and Power, 35 (2). pp. 403-412. ISSN 0748-4658. doi:10.2514/1.b37133.

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Increased background pressure in vacuum chamber test facilities as compared to on-orbit operation has been shown to influence the operation of electric propulsion devices such as Hall thrusters. This study aims to elucidate the impact of pressure on the ionization and acceleration mechanisms in a stationary plasma thruster, model SPT-100 Hall thruster, using time-averaged and time-resolved laser-induced fluorescence velocimetry. The results are compared for the thruster operating at an applied 300 V (∼4.25  A), with vacuum facility background pressures ranging from 1.7×10^(−5) to 8.0×10^(−5)  torr. Time-averaged measurements reveal that, in general, an upstream shift in the position of the ionization and acceleration regions occurs as the facility pressure is increased above the nominal 1.7×10^(−5)  torr. Time-resolved measurements, implemented using a sample-hold scheme with 1  μs resolution, emphasize that similar acceleration profiles are present within the Hall thruster discharge channel regardless of background pressure. Measurements taken at 3.5×10^(−5)  torr, where the facility background neutral density is similar to the neutral density emitted from the thruster, unexpectedly show increased ion acceleration over the next highest pressure condition at 5.0×10^(−5)  torr. These results indicate a not-yet well defined balance of the impacts of neutral ingestion, classical and turbulent electron transport on thruster operation, and that the ratio of the background to thruster neutral density is a more relevant benchmark than background pressure alone when evaluating Hall thruster operation.

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Additional Information:This material is declared a work of the U.S. Government and is not subject to copyright protection in the United States. Received 18 May 2018; revision received 1 October 2018; accepted for publication 16 October 2018; published online Open Access 3 January 2019. This work is sponsored in part by the U.S. Air Force Office of Scientific Research, with M. Kendra as Program Manager.
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Air Force Office of Scientific Research (AFOSR)UNSPECIFIED
Issue or Number:2
Record Number:CaltechAUTHORS:20190228-145311534
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Official Citation:Background Pressure Effects on Ion Velocity Distributions in an SPT-100 Hall Thruster. Natalia MacDonald-Tenenbaum, Quinn Pratt, Michael Nakles, Nickolas Pilgram, Michael Holmes, and William Hargus Jr. Journal of Propulsion and Power 2019 35:2, 403-412
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:93362
Deposited By: Tony Diaz
Deposited On:28 Feb 2019 23:03
Last Modified:16 Nov 2021 16:57

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