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Multiple sensor multifrequency eddy current monitor for solidification and growthA compact cylindrical multisensor eddy current measuring system with integral furnace was develop to monitor II-VI crystal growth to provide interfacial information, solutal segregation, and conductivities of the growth materials. The use of an array of sensors surrounding the furnace element allows one to monitor the volume of interest. Coupling these data with inverse multifrequency analysis allows radial conductivity profiles to be generated at each sensor position. These outputs were incorporated to control the processes within the melt volume. The standard eddy current system functions with materials whose electric conductivities are as low as 2E2 Mhos/m. A need was seen to extend the measurement range to poorly conducting media so the unit was modified to allow measurement of materials conductivities 4 order of magnitude lower and bulk dielectric properties. Typically these included submicron thick films and semiinsulating GaAs. This system was used to monitor complex heat transfer in grey bodies as well as semiconductor and metallic solidification.
Document ID
19910012049
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Wallace, John (Casting Analysis Corp. Weyers Cave, VA, United States)
Date Acquired
September 6, 2013
Publication Date
May 1, 1990
Publication Information
Publication: JPL, Proceedings of the First Workshop on Containerless Experimentation in Microgravity
Subject Category
Materials Processing
Accession Number
91N21362
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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