Deep Space 1 Flight Spare Ion Thruster 30,000-Hour Life Test

摘要

The extended-life test of the Deep Space 1 flight spare ion thruster was voluntarily terminated on 26 June 2003.nDuring its five-year run, the thruster operated for a total of 30,352 h, processed 235.1 kg of xenon propellant, andndemonstrated extended operation at multiple throttled conditions. The objectives of the test were to characterizenfailure modes and quantify thruster performance as a function of engine wear and throttle level. Degradationnprocesses included erosion of the discharge cathode keeper, accelerator-grid sputter erosion, and deposition ofnmaterial in the neutralizer cathode at low power. Performance degradation was limited to a reduction in measurednthrust at the full-power point for the final 1000 h of operation. Posttest inspection of the engine was initiated followingnthe test termination to ascertain causes of the wear and to look for any previously unknown wear processes.nSignificant findings included facility-induced flakes in the discharge chamber, the presence of through-pits in thenaccelerator-grid webbing, significant erosion of the discharge cathode orifice plate, and healthy cathode inserts. Ansummary of the beginning-of-test and end-of-test performances and results of the posttest destructive evaluation arenpresented.