Dielectric properties of some insulating materials over the temperature range 4·2–300° K

✍ Scribed by M.J. Chant

• Publisher: Elsevier Science
• Year: 1967
• Tongue: English
• Weight: 315 KB
• Volume: 7
• Category: Article
• ISSN: 0011-2275
• DOI: 10.1016/0011-2275(67)90009-4

✦ Synopsis

electrical apparatus will depend, not only on the performance of the superconductors, but also on the limitation of heat from other sources, such as leakage through the thermal insulation and dielectric loss. The latter, which contributes a negligible proportion of the total heat in the apparatus when operating at normal temperature, could produce excessive heating at liquid helium temperature. There is also a possibility of building apparatus with copper or aluminium conductors to work at liquid hydrogen temperature (20 ° K); although dielectric losses are not so serious at this temperature, unsuitable materials could add considerably to the heat to be removed.

As few data 1,2 were available on dielectrics at these very low temperatures, the properties of several materials which could be used in sheet form have been determined. This paper describes the equipment used for the measurement of dielectric constant and loss tangent (tan 3) over the temperature range 4.2-300 ° K at 75 c/s, and at 4"2 ° K over the frequency range 75-1 000 c/s, and gives results

~" Physics and General Engineering Group, English Electric,