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Anode power deposition in magnetoplasmadynamic thrustersResults of anode heat-flux and anode fail measurements from a multimegawatt self-field quasi-steady magnetoplasmadynamic (MPD) thruster are presented. Measurements were obtained with argon and helium propellants for a variety of currents and mass flow rates. Anode heat flux was directly measured with thermocouples attached to the inner surface of a hollowed section. Anode falls were determined both from floating probes and through heat flux measurements. Comparison of data acquired through either method shows excellent agreement. Anode falls varied between 4-50 V with anode power fractions reaching 70 percent with helium at 150 kW, and 50 percent with argon at 1.9 MW. The anode fall was found to correlate well with electron Hall parameters calculated from triple Langmuir and magnetic probe data collected near the anode. Two possible explanations for this result are proposed: (1) the establishment of large electric fields at the anode to maintain current conduction across the strong magnetic fields; and (2) anomalous resistivity resulting from the onset of microturbulence in the plasma. To investigate the latter hypothesis, electric field, magnetic field, and current density profiles measured in the vicinity of the anode were incorporated into Ohm's law to estimate the electrical conductivity. Results of this analysis show a substantial deviation of the measured conductivity from that calculated with classical formulas. These results imply that anomalous effects are present in the plasma near the anode.
Document ID
19930050483
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Gallimore, A. D.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Kelly, A. J.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Jahn, R. G.
(Princeton Univ. NJ, United States)
Date Acquired
August 16, 2013
Publication Date
June 1, 1993
Publication Information
Publication: Journal of Propulsion and Power
Volume: 9
Issue: 3
ISSN: 0748-4658
Subject Category
Spacecraft Propulsion And Power
Accession Number
93A34480
Funding Number(s)
CONTRACT_GRANT: JPL-954997
Distribution Limits
Public
Copyright
Other

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