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Plasma fluctuations in a Kaufman thrusterMeasurements of the RMS magnitude, spectra and cross-correlations for the fluctuations in the beam, discharge and neutralizer keeper currents are presented for a 30-cm diameter dished grid ion thrustor for a range of magnetic baffle currents and up to 2.0 amperes beam current. The ratio of RMS to mean ion beam current varied from 0.04 to 0.23. The spectra of the amplitudes of the beam and discharge current fluctuations were taken up to 9 MHz and show that the predominant amplitudes occur at frequencies of 10 kHz or below. The fall-off with increasing frequency is rapid. Frequencies above 100 kHz the spectral levels are 45 kb or more below the maximum peak amplitudes. The cross-correlations revealed the ion beam fluctuations to have large radial and axial scales which implied that the beam fluctuates as a whole or 'in-phase.' The cross-correlations of the beam and neutralizer keeper current fluctuations indicated the neutralizer contributions to the beam fluctuations to be small, but not negligible. The mode of operation of the thrustor (values of beam and magnetic baffle currents) was significant in determining the RMS magnitude and spectral shape of the beam fluctuations. The major oscillations were not found to be directly dependent on the power conditioner inverter frequencies.
Document ID
19740027904
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Serafini, J. S.
Terdan, F. F.
(NASA Lewis Research Center Cleveland, Ohio, United States)
Date Acquired
August 7, 2013
Publication Date
October 1, 1973
Subject Category
Propulsion Systems
Report/Patent Number
AIAA PAPER 73-1056
Meeting Information
Meeting: Electric Propulsion Conference
Location: Lake Tahoe, NV
Start Date: October 31, 1973
End Date: November 2, 1973
Sponsors: American Institute of Aeronautics and Astronautics
Accession Number
74A10654
Distribution Limits
Public
Copyright
Other

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