Extended Lifetime Low Power Hall Thrusters

Busek's 200 W Hall thruster has been flight qualified for the TechSat 21 program and more recently for the RoadRunner Program. During life testing conducted at AFRL the BHT-200 operation was approximately 900 hours less than the Phase II IHPRPT Goal of approximately 1000 hours. Concurrent with the IHPRPT demonstration test, Busek identified several design modifications in the Phase I SBIR that lessen the erosion of the dielectric insulators. Based on measured erosion profiles during 500 hours of testing, the extrapolated life of the extended lifetime thruster is 1500-2000 hours. Many emerging Space Test Program (STP), and orbit transfer missions require lifetime magnitudes of 3000 hours. Therefore, the focus of the Phase II effort is to extend the lifetime of the BHT-200 to 3000 hours making it attractive to a broader range of users. In the Phase II, Busek will continue with design modifications, primarily to the neutral flow distribution and magnetic field profiles that minimize the impingement of ions onto the insulator surfaces. In parallel, sputter resistant materials will be evaluated as substitutes to the baseline boron nitride. At the conclusion of the Phase II program, Busek will build an engineering model thruster and conduct an accelerated life test using results from a lifetime model being developed by our subcontractor MIT to predict erosion rates. Pending a positive outcome of the accelerated lifetime prediction/validation the thruster will be transferred to AFRL for continued life testing.