NASA LogoNTRSNTRS - NASA Technical Reports ServerSearchmore_vertCollectionsAboutNewsHelpLogin Back to ResultsInception of Snapover and Gas Induced Glow DischargesGround based experiments of the snapover phenomenon were conducted in the large vertical simulation chamber at the Glenn Research Center (GRC) Plasma Interaction Facility (PIF). Two Penning sources provided both argon and xenon plasmas for the experiments. The sources were used to simulate a variety of ionospheric densities pertaining to a spacecraft in a Low Earth Orbital (LEO) environment. Secondary electron emission is believed responsible for dielectric surface charging, and all subsequent snapover phenomena observed. Voltage sweeps of conductor potentials versus collected current were recorded in order to examine the specific charging history of each sample. The average time constant for sample charging was estimated between 25 and 50 seconds for all samples. It appears that current drops off by approximately a factor of 3 over the charging time of the sample. All samples charged in the forward and reverse bias directions, demonstrated hysteresis. Current jumps were only observed in the forward or positive swept voltage direction. There is large dispersion in tile critical snapover potential when repeating sweeps on any one sample. The current ratio for the first snapover region jumps between 2 and 4.6 times, with a standard deviation less than 1.6. Two of the samples showed even larger current ratios. It is believed the second large snapover region is due to sample outgassing. Under certain preset conditions, namely at the higher neutral gas background pressures, a perceptible blue-green glow was observed around the conductor. The glow is believed to be a result of secondary electrons undergoing collisions with an expelled tenuous cloud of gas, that is outgassed from the sample. Spectroscopic measurements of the glow discharge were made in an attempt to identify specific lines contributing to the observed glow.Document ID20000021586Acquisition SourceGlenn Research CenterDocument TypeTechnical Memorandum (TM)AuthorsGalofaro, J. T.*(NASA Glenn Research Center Cleveland, OH United States)*Vayner, B. V.*(Ohio Aerospace Inst. Brook Park, OH United States)*Degroot, W. A.*(DYNACS Engineering Co., Inc. Brook Park, OH United States)*Ferguson, D. C.*(NASA Glenn Research Center Cleveland, OH United States)*Thomson, C. D.*(Utah State Univ. Logan, UT United States)*Dennison, J. R.*(Utah State Univ. Logan, UT United States)*Davies, R. E.*(Utah State Univ. Logan, UT United States)*Date AcquiredSeptember 7, 2013Publication DateJanuary 1, 2000Subject CategoryPlasma PhysicsReport/Patent NumberNAS 1.15:209645NASA/TM-2000-209645E-11991Funding Number(s)PROJECT: RTOP 632-1A-1LDistribution LimitsPublicCopyrightWork of the US Gov. Public Use Permitted.Available DownloadsNameType20000021586.pdfSTIcloud_downloadcontent_copyvisibilityRelated RecordsThere are no records associated with this record.visibility_offNo Preview Available
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