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Using Si Diodes To Detect H2 Liquid/Vapor InterfacesCommercially available silicon-diode temperature sensors used to detect interfaces between hydrogen liquid and hydrogen vapor at steady-state saturation conditions. Sensors mounted at short intervals along rod to form rake-like array. Array inserted in tank with rod oriented vertically, where it senses level of liquid hydrogen to resolution equal to interval between sensors. Basic idea to measure voltage across sensor while supplying small electric current that heats sensor. Because vapor cools sensor less effectively than liquid does, sensor's steady-state temperature greater when sensor surrounded by vapor than when immersed in liquid. Voltage output decreases as temperature increases for silicon diodes. Thus, temperature (voltage) reading used to determine whether liquid level above or below sensor.
Document ID
19940000628
Acquisition Source
Legacy CDMS
Document Type
Other - NASA Tech Brief
Authors
Dempsey, Paula Jean
(NASA Lewis Research Center, Cleveland, OH.)
Fabik, Richard
(NASA Lewis Research Center, Cleveland, OH.)
Date Acquired
August 16, 2013
Publication Date
November 1, 1994
Publication Information
Publication: NASA Tech Briefs
Volume: 18
Issue: 11
ISSN: 0145-319X
Subject Category
Physical Sciences
Report/Patent Number
LEW-15860
Accession Number
94B10628
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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