NASA's Evolutionary Xenon Thruster (NEXT) Prototype Model 1R (PM1R) ion thruster and propellant management system wear test results [electronic resource] / Jonathan L. Van Noord and George C. Soulas, James S. Sovey ; prepared for the 31st International Electric Propulsion Conference (IEPC 2009) cosponsored by Aerojet, A.F. Offi ce of Scientifi c Research, AFRL, Busek Company, Inc., CU Aerospace, ERPS, EDA, Inc., L3 Communications, Michigan Space Grant Consortium/NASA, and Michigan Engineering, Ann Arbor, Michigan, September 20-24, 2009.