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Investigation of energy transfer in the ignition mechanism of a NASA standard initiatorThe principal objective of the proposed research was to construct a detailed computer model of the NASA Standard Initiator (NSI). The NSI plays a critical role in initiating various pyrotechnic events in the National Space Transportation System and is also used in Shuttle payload applications. Several initiators failed when being tested at very low temperatures (4 to 20 K). During subsequent investigation an unacceptable high failure rate was found even at higher temperatures (100 to 150 K) but the precise cause of failure was not determined. The modelling work was undertaken to investigate reasons for failure and to predict the performance of alternate firing schemes. The work has shown that the most likely cause of failure at low temperature is poor thermal contact between the electrically heated bridgewire and the pyrotechnic charge. This problem may be masked if there is good thermal contact between the bridgewire and the alumina charge cup. The high thermal conductivity of alumina at cryogenic temperatures was overlooked in previous analyses, which assumed that the charge cup acted as a thermal insulator.
Document ID
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Varghese, Philip L.
(Texas Univ. Austin, TX, United States)
Date Acquired
September 5, 2013
Publication Date
January 1, 1988
Subject Category
Spacecraft Propulsion And Power
Report/Patent Number
NAS 1.26:184673
Accession Number
Funding Number(s)
Distribution Limits
Work of the US Gov. Public Use Permitted.
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