A low-cost optical approach to evaluate the Life time of Hall thruster discharge channel
This paper will present a novel procedure for performing accelerated wear test on Hall thruster discharge channels. The procedure takes advantage of a number of recent advances in optical diagnostics that have enabled increasingly accurate non-intrusive determination of both the length of the erosion zone and the erosion rate of the discharge channels in a Hall thruster. In the proposed procedure, two-axis laser-induced fluorescence is used to determine the energy and direction of the singly-charged ions responsible for the majority of the channel erosion. This data can then be used to determine the starting depth of the erosion zone inside the channel. It can also potentially be correlated to the angles of the chamfers at the end of the life of the channels. If it is determined that the predicted shape of the channels at the end of life intersect with the magnetic poles, an accelerated wear test can be performed to determine the amount of time to reach pole-exposure. This accelerated life test would involve the use of laser-induced fluorescence and cavity ring-down spectroscopy to accurately predict the change in the shape of the discharge channels in short time steps. The paper will describe in detail each step of this novel procedure, the assumptions made at each step, and the current body of scientific evidence that support these assumptions. © 2012 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.
