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Efficient Ionization Investigation for Flow Control and Energy ExtractionNonequilibrium ionization of air by nonthermal means is explored for hypersonic vehicle applications. The method selected for evaluation generates a weakly ionized plasma using pulsed nanosecond, high-voltage discharges sustained by a lower dc voltage. These discharges promise to provide a means of energizing and sustaining electrons in the air while maintaining a nearly constant ion/neutral molecule temperature. This paper explores the use of short approx.5 nsec, high-voltage approx.12 to 22 kV, repetitive (40 to 100 kHz) discharges in generating a weakly ionized gas sustained by a 1 kV dc voltage in dry air at pressures from 10 to 80 torr. Demonstrated lifetimes of the sustainer discharge current approx.10 to 25 msec are over three orders of magnitude longer than the 5 nsec pulse that generates the electrons. This life is adequate for many high speed flows, enabling the possibility of exploiting weakly ionized plasma phenomena in flow-fields such as those in hypersonic inlets, combustors, and nozzles. Results to date are obtained in a volume of plasma between electrodes in a bell jar. The buildup and decay of the visible emission from the pulser excited air is photographed on an ICCD camera with nanosecond resolution and the time constants for visible emission decay are observed to be between 10 to 15 nsec decreasing as pressure increases. The application of the sustainer voltage does not change the visible emission decay time constant. Energy consumption as indicated by power output from the power supplies is 194 to 669 W depending on pulse repetition rate.
Document ID
20090034479
Acquisition Source
Glenn Research Center
Document Type
Technical Memorandum (TM)
Authors
Schneider, Steven J.
(NASA Glenn Research Center Cleveland, OH, United States)
Kamhawi, Hani
(NASA Glenn Research Center Cleveland, OH, United States)
Blankson, Isaiah M.
(NASA Glenn Research Center Cleveland, OH, United States)
Date Acquired
August 24, 2013
Publication Date
September 1, 2009
Subject Category
Plasma Physics
Report/Patent Number
AIAA Paper 2009-1050
E-16999
NASA/TM-2009-215657
Funding Number(s)
WBS: WBS 599489.02.07.03.04.04
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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