We present a theoretical study of the electron and nuclear dynamics that would arise in an attosecond two-color XUV-pump/XUV-probe experiment in glycine. In this scheme, the broadband pump pulse suddenly...
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)10-08-2011 REPORT TYPE Conference Paper DATES COVERED (From -To) TITLE AND SUBTITLE 5a. CONTRACT NUMBER A Performance Comparison of Xenon and Krypton Propellant on an SPT-100 Hall SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S)Air Force Research Laboratory (AFMC) AFRL/RZS SPONSOR/MONITOR'S Pollux Drive NUMBER(S)Edwards AFB CA 93524-7048 AFRL-RZ-ED-TP-2011-342 DISTRIBUTION / AVAILABILITY STATEMENTApproved for public release; distribution unlimited (PA #11558). SUPPLEMENTARY NOTESFor presentation at the 32 nd International Electric Propulsion Conference, Wiesbaden, Germany, 11-15 Sep 2011. ABSTRACTThe use of krypton as an alternative to xenon for Hall thruster propellant is an interesting option for satellite system designers due to its lower cost. However, this cost-savings comes at the expense of thrust efficiency. Reduction in efficiency can be caused by energy losses from Joule heating, radiation, and the ionization process as well as degradation of plume quality from an increase in velocity distribution spread (most often from an increase in multiply charged ion populations) and geometric beam divergence.1 In order to quantify this performance reduction for the case of the flight model SPT-100 HET (1.35 kW), an ongoing series of experimental measurements is being conducted to measure how various thruster efficiency terms change with propellant and operating condition. This study will combine thrust measurements with plume data from electrostatic probes. This paper presents the results of performance measurements made using an inverted pendulum thrust stand. Krypton operating conditions were tested over a large range of operating powers from 800 W to 3.9 kW. Analysis of how performance is impacted by propellant and operating condition is presented. A simple mission analysis was done based on these measurements to evaluate the practicality of krypton propellant for an SPT-100 subsystem using krypton propellant for north-south station keeping (NSSK) for a typical communications spacecraft in geosynchronous orbit.. SUBJECT TERMS
Increasing demand for larger and more efficient geostationary communication spacecraft in the recent years has greatly increased the demand for electric propulsion subsystems. As a result Space Systems Loral SSL has decided to leverage the heritage of the very successful SPT-100 subsystem to develop a new SPT-140 subsystem. New market requirements were taken into account along with lessons learned from 35,000+ hours of in-orbit Hall Effect Thruster operations on SSL spacecraft. The new subsystem centers around the EDB Fakel manufactured SPT-140. Two qualification models were built: A life test unit and a systems test unit. Qualification model 001 (QM001) has undergone acceptance, qualification level testing, and has accumulated 6000+ hours of operation to date in a life test which will conclude with a total impulse of 8.17 MN-sec. Qualification model 002 (QM002) is a systems test unit which has been delivered to SSL post-acceptance testing. The unit has since completed plume characterization and performance testing at NASA GRC and The Aerospace Corporation. Testing with QM002 will continue through 2013 with a full end-toend test being performed using a qualification model PPU, harness, and flight positioning mechanism. This paper is a summary of testing to date and an overview of future works.
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