Procedure of Predicting the Lifetime of the Accelerating Electrode of an Ion-Extraction System of a Gas-Discharge Ion Source

Abstract

The state of studies on determination of the lifetime of ion thrusters (IT), including their methodology, is analyzed. The erosion of the accelerating electrode (AE) of an ion-extraction system caused by charge-exchange ions is a critical process responsible for the IT lifetime. It is shown that the quickest and most accurate information on the nature of AE erosion and rate at the initial test stage can be obtained by a method based on the use of multilayer coatings, consisting of several pairs of optical contrast materials, preliminarily applied to the AE surface. The method allows the use of simple photographic devices for recording the erosion pattern and is especially efficient in the case of a highly nonuniform nature of erosion. The calculation procedure is presented for the parameters of diagnostic multilayer coatings, including the optimal layer thickness and total coating thickness, which allow data to be obtained on the surface erosion profile and rate, and on the charge-exchange ion current density distribution with the highest resolution during the given test time.