Angularly resolved ion species fractions of Xe +1 , Xe +2 , and Xe +3 in the Busek BHT-200-X3 xenon Hall thruster plume were measured using an ExB probe for several operating conditions. The thruster was operated at nominal anode potential of 250 V and swept from 200 V to 325 V in 25 V increments. The ExB probe was placed 60 cm downstream of the exit plane and rotated up to 90 o from centerline. At the nominal anode potential, the ion species fractions of the multiply charged xenon ions were lower, while at increased discharged voltages Xe +2 and Xe +3 showed an increase in their respective species fractions. At angles beyond 35 o , an additional low energy peak was observed suggesting additional collisions in the farfield produce these low energy ions. Our goals are to characterize the thruster ion distribution and to verify predictions of various numerical models by investigating the effects of thruster operation and chamber backpressure on the production of charge exchange ions.
Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY) 23-05-2006 REPORT TYPE Technical Paper ABSTRACTTo better characterize the potential impacts of the operation of a Busek Company, Inc. BHT-HD-600 laboratory Hall thruster on spacecraft, a number of plume properties have been measured. These include current density using a Faraday probe, ion energy distribution using a retarding potential analyzer, and ion species fractions using an E x B probe. The BHT-HD-600 Hall thruster is a nominally 600 W xenon Hall thruster developed by Busek Co. Inc. for the U.S. Air Force Research Laboratory. Plume characterization of Hall thrusters is required to fully understand the impacts of thruster operation on spacecraft. Much of these plume data are vital inputs for numerical models that can then be applied to estimate the effect of the energetic plume on complex spacecraft geometries. Early measurement of plume properties, such as plume divergence, ion energy distribution, and species fractions, aids the timely transfer of Hall thruster technology to the user. The plume's ion beam was characterized by measurement of ion current density radial profiles, ion energy spectra and ion species fraction distributions. Measurements were recorded ±90 o off thruster centerline at 60 cm from the discharge. It was determined slight variations in anode potential and mass-flow produced a measurable effect on ion current density and plume divergence, experimentally showing an increase or decrease of ±15-20%. Ionic energy spectra demonstrated both inelastic and elastic scattering within the plume. The measurements reveal significant populations of multiplycharged ions in the plume. E x B probe measurements show surprisingly ion species fraction angle dependence.
Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S)Air Force ABSTRACTNumerical modeling of the expansion of electric thruster plumes provides direct means for predicting spacecraft surface contamination and erosion due to plume ions. A software package named COLISEUM that is capable of self-consistently modeling plasma propagation and interactions with arbitrary 3-D surfaces is being developed by a national team of researchers. Despite much research and development in modeling plume expansion, it is necessary to continuously validate these codes using laboratory based experimental data. It is well-established that vacuum chamber facilities affect the plume of these devices. Thus, the models must not only describe the plume expansion, but also effects of the vacuum chamber. COLISEUM has been designed to simulate both vacuum chamber configurations and spacecraft geometries. This work provides source derivation from laser induced florescence (LIF) data. Included is a study that compares results from a hybrid particle-in-cell model (AQUILA) with Monte Carlo collisions to data obtained from the plume of Busek 600W Hall thruster (BHT-HD-600). This data includes current density, velocity distribution, and energy data. Numerical modeling of the expansion of electric thruster plumes provides direct means for predicting spacecraft surface contamination and erosion due to plume ions. A software package named COLISEUM that is capable of self-consistently modeling plasma propagation and interactions with arbitrary 3-D surfaces is being developed by a national team of researchers. Despite much research and development in modeling plume expansion, it is necessary to continuously validate these codes using laboratory based experimental data. It is well-established that vacuum chamber facilities affect the plume of these devices. Thus, the models must not only describe the plume expansion, but also effects of the vacuum chamber. COLISEUM has been designed to simulate both vacuum chamber configurations and spacecraft geometries. This work presents a study that compares results from a hybrid particle-in-cell model (AQUILA) with Monte Carlo collisions to data obtained from the plume of Busek 600W Hall thruster (BHT-HD-600). This data includes current density, ion velocities, and energy distribution data. Also contained in this work is a source derivation description from laser induced fluorescence (LIF) data.
Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY) SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S)Air Force Research Laboratory (AFMC) AFRL/PRS SPONSOR/MONITOR'S Pollux Drive NUMBER(S)Edwards AFB CA 93524-7048 AFRL-PR-ED-TP-2007-381 DISTRIBUTION / AVAILABILITY STATEMENTApproved for public release; distribution unlimited (PA #07318A). ABSTRACTThis work attempts to determine angular dependence curves for sputter rates of a material based on a single experimental measurement. An aluminum cylinder was exposed to a BHT-200 plume, and the resulting erosion profile was measured. This profile was fed into an optimizer, which calculated the angular dependence curve to match the given erosion profile. The calculated profile matched well with the experimental profile; however, neither matched well with previously published results. The likely cause of this discrepancy was the non-uniformity of the ion source used. As a further validation of the optimization routine, the angular dependence curve was input to the COLISEUM plasma modeling code, which generated the same erosion profile as the experimental data. Abstract: This work attempts to determine angular dependence curves for sputter rates of a material based on a single experimental measurement. An aluminum cylinder was exposed to a BHT-200 plume and the resulting erosion profile was measured. This profile was fed into an optimizer, which calculated the angular dependence curve to match the given erosion profile. The calculated profile matched well with the experimental profile, however neither matched well will previously published results. The likely cause of this discrepancy was the non-uniformity of the ion source used. As a further validation of the optimization routine, the angular dependence curve was input to the Coliseum plasma modeling code, which generated the same erosion profile as the experimental data.
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