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In-Situ Measurement of Hall Thruster Erosion Using a Fiber Optic Regression ProbeOne potential life-limiting mechanism in a Hall thruster is the erosion of the ceramic material comprising the discharge channel. This is especially true for missions that require long thrusting periods and can be problematic for lifetime qualification, especially when attempting to qualify a thruster by analysis rather than a test lasting the full duration of the mission. In addition to lifetime, several analytical and numerical models include electrode erosion as a mechanism contributing to enhanced transport properties. However, there is still a great deal of dispute over the importance of erosion to transport in Hall thrusters. The capability to perform an in-situ measurement of discharge channel erosion is useful in addressing both the lifetime and transport concerns. An in-situ measurement would allow for real-time data regarding the erosion rates at different operating points, providing a quick method for empirically anchoring any analysis geared towards lifetime qualification. Erosion rate data over a thruster's operating envelope would also be useful in the modeling of the detailed physics inside the discharge chamber. A recent fundamental sensor development effort has led to a novel regression, erosion, and ablation sensor technology (REAST). The REAST sensor allows for measurement of real-time surface erosion rates at a discrete surface location. The sensor was tested using a linear Hall thruster geometry, which served as a means of producing plasma erosion of a ceramic discharge chamber. The mass flow rate, discharge voltage, and applied magnetic field strength could be varied, allowing for erosion measurements over a broad thruster operating envelope. Results are presented demonstrating the ability of the REAST sensor to capture not only the insulator erosion rates but also changes in these rates as a function of the discharge parameters.
Document ID
20090014104
Acquisition Source
Marshall Space Flight Center
Document Type
Conference Paper
Authors
Polzink, Kurt A.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Korman, Valentin
(K Sciences, LLC Huntsville, AL, United States)
Date Acquired
August 24, 2013
Publication Date
December 8, 2008
Subject Category
Spacecraft Propulsion And Power
Report/Patent Number
MSFC-2182
Meeting Information
Meeting: 3rd Spacecraft Propulsion Subcommittee (SPS) JANNAF meeting
Location: Orlando, FL
Country: United States
Start Date: December 8, 2008
End Date: December 12, 2008
Sponsors: Department of the Army, Department of the Navy, NASA Headquarters, Department of the Air Force
Distribution Limits
Public
Copyright
Other

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