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Evaluation of high specific-heat ceramic for regenerator use at temperatures between 2-30 KSpecific heat, thermal conductivity (both in the range 2-30 K), and microhardness data were measured on the ceramics labelled LS-8, LS-8A, and LS-8A doped with CsI, SnCl2, and AgCl. A work hardened sample of LS-8A was also studied in an effort to determine the feasibility of using these types of LS-8 materials to replace Pb spheres in the regenerator of the JPL cryocooler. The LS-8A materials are all more than an order of magnitude harder than Pb, and the dopants do not significantly improve the hardness. However, the SnCl2 dopant has a remarkable effect in improving the specific heat and thermal conductivity of LS-8A. The SnCl2 doping level which maximized the regenerator enthalpy change in going from an unloaded to a loaded condition was found to be 0.2 percent SnCl2 in LS-8A. It was also found that the enthalpy change for a regenerator employing the LS-8A material is more than three times larger than for the Pb spheres case. The use of rods, rather than spheres, of optimally doped LS-8A in regenerators is discussed.
Document ID
19810007724
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Lawless, W. N. (Lake Shore Cryotronics, Inc. Westerville, OH, United States)
Date Acquired
September 4, 2013
Publication Date
December 1, 1979
Subject Category
Nonmetallic Materials
Report/Patent Number
NASA-CR-163888
JPL-9950-458
Accession Number
81N16240
Funding Number(s)
CONTRACT_GRANT: NAS7-100
CONTRACT_GRANT: JPL-955446
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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