NASA LogoNTRSNTRS - NASA Technical Reports ServerSearchmore_vertCollectionsAboutNewsHelpLogin Back to ResultsDesign of a power management and distribution system for a thermionic-diode powered spacecraftThe Electrical Systems Development Branch of the Power Technology Division at the NASA Lewis Research Center in Cleveland, Ohio is designing a Power Management and Distribution (PMAD) System for the Air Force's Integrated Solar Upper Stage (ISUS) Engine Ground Test Demonstration (EGD). The ISUS program uses solar-thermal propulsion to perform orbit transfers from Low Earth Orbit (LEO) to Geosynchronous Orbit (GEO) and from LEO to Molnya. The ISUS uses the same energy conversion receiver to perform the LEO to High Earth Orbit (HEO) transfer and to generate on-orbit electric power for the payloads. On-orbit power generation is accomplished via two solar concentrators heating a dual-cavity graphite-core which has Thermionic Diodes (TMD's) encircling each cavity. The graphite core and concentrators together are called the Receiver and Concentrator (RAC). The TDM-emitters reach peak temperatures of approximately 2200K, and the TID-collectors are run at approximately 1000K. Because of the high Specific Impulse (I(sup sp)) of solar thermal propulsion relative to chemical propulsion, and because a common bus is used for communications, GN&C, power, etc., a substantial increase in payload weight is possible. This potentially allows for a stepdown in the required launch vehicle size or class for similar payload weight using conventional chemical propulsion and a separate spacecraft bus. The ISUS power system is to provide 1000W(sub e) at 28+/-6V(sub dc) to the payload/spacecraft from a maximum TID generation capability of 1070W(sub e) at 2200K. Producing power with this quality, protecting the spacecraft from electrical faults and accommodating operational constraints of the TID's are the responsibilities of the PMAD system. The design strategy and system options examined along with the proposed designs for the Flight and EGD configurations are discussed herein.Document ID19960049743Acquisition SourceLegacy CDMSDocument TypeConference PaperAuthorsKimnach, Greg L.*(NASA Lewis Research Center Cleveland,OH United States)*Date AcquiredSeptember 6, 2013Publication DateAugust 1, 1996Subject CategorySpacecraft Propulsion And PowerReport/Patent NumberNASA-TM-107298E-10376NAS 1.15:107298Meeting InformationMeeting: Intersociety Energy Conversion Engineering ConferenceLocation: Washington, DCCountry: United StatesStart Date: August 11, 1996End Date: August 16, 1996Sponsors:American Nuclear Society,American Inst. of Aeronautics and Astronautics,Society of Automotive Engineers, Inc.,American Society of Mechanical Engineers,American Inst. of Chemical Engineers,Institute of Electrical and Electronics EngineersAccession Number96N33994Funding Number(s)PROJECT: RTOP 233-1A-B4Distribution LimitsPublicCopyrightWork of the US Gov. Public Use Permitted.Available DownloadsNameType19960049743.pdfSTIcloud_downloadcontent_copyvisibilityRelated RecordsThere are no records associated with this record.visibility_offNo Preview Available
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