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Physical model and experimental results of cathode erosion related to power supply rippleThis paper discusses the physical effects of power supply ripple on cathode erosion and cathode arc attachment in a water-cooled, 30 kW nitrogen arcjet. Experimental results are presented for 2 percent thoriated tungsten, which show that the long-term cathode erosion rate is a decreasing function of current ripple over the range 1-13 percent. Above this range, the cathode discharge becomes unstable, and the erosion rate rapidly increases. A qualitative model of this effect is given in terms of a magnetically induced radial motion of the arc column, and an overall increase in the cathode spot radius due to the higher peak current associated with higher ripple. The most important effect of power supply ripple is therefore shown to be its ability to collectively drive the cathode attachment away from the cathode center. This leads to an increase in the cathode attachment area, and a subsequent decrease in the cathode erosion rate.
Document ID
19920071571
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Harris, W. J.
(NASA Headquarters Washington, DC United States)
O'Hair, E. A.
(NASA Headquarters Washington, DC United States)
Hatfield, L. L.
(NASA Headquarters Washington, DC United States)
Kristiansen, M.
(Texas Tech University Lubbock, United States)
Date Acquired
August 15, 2013
Publication Date
July 1, 1992
Subject Category
Spacecraft Propulsion And Power
Report/Patent Number
AIAA PAPER 92-3837
Accession Number
92A54195
Funding Number(s)
CONTRACT_GRANT: NGT-50635
Distribution Limits
Public
Copyright
Other

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