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Assessments of Hollow Cathode Wear in the Xenon Ion Propulsion System (XIPs(c)) by Numerical Analyses and Wear TestsThe standard approach presently followed by NASA to qualify electric propulsion for the required mission throughput has been based largely on life tests, which can be costly and time consuming. Revised electric propulsion lifequalification approaches are being formulated that combine analytical and/or computational methods with (shorter-duration) wear tests. As a model case, a wear test is being performed at JPL to assess the lifetime of the discharge hollow cathode in the Xenon Ion Propulsion System (XIPS(c)), a 25-cm ion engine developed by L-3 Communications Electron Technologies, Inc. for commercial applications. Wear and plasma data accumulated throughout this life-assessment program are being used to validate the existing 2-D hollow cathode code OrCa2D. We find that the OrCa2D steady-state solution predicts very well the time-averaged plasma data and the keeper voltage after 5500 hrs of operation in high-power mode. When the wave motion that occurs naturally in these devices is accounted for, based on an estimate of the maximum wave amplitude, the molybdenum-keeper erosion profile observed in the XIPS(c) discharge cathode is also reproduced within a factor of two of the observation. When the same model is applied to predict the erosion of a tantalum keeper we find that erosion is reduced by more than two orders of magnitude compared to the molybdenum keeper due the significantly lower sputtering yield of tantalum. A tantalum keeper would therefore allow keeper lifetimes that greatly exceed the present requirements for deep-space robotic missions considered by NASA. Moreover, such large reduction of the erosion renders the largest uncertainties in the models, which are associated with the wave amplitude estimates and the electron transport model, negligible.
Document ID
20150014760
Acquisition Source
Jet Propulsion Laboratory
Document Type
Conference Paper
External Source(s)
Authors
Mikellides, Ioannis G.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Katz, Ira
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Goebel, Dan M.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Polk, James E.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Date Acquired
August 3, 2015
Publication Date
July 21, 2008
Subject Category
Spacecraft Propulsion And Power
Numerical Analysis
Meeting Information
Meeting: AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit
Location: Hartford, CT
Country: United States
Start Date: July 21, 2008
End Date: July 23, 2008
Sponsors: American Society for Electrical Engineers, Society of Automotive Engineers, Inc., American Society of Mechanical Engineers, American Inst. of Aeronautics and Astronautics
Distribution Limits
Public
Copyright
Other
Keywords
plasma simulations
electric propulsion

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