Dielectric strength of some insulators at cryogenic temperatures

✍ Scribed by K. Kobayashi; H. Takebe

• Publisher: Elsevier Science
• Year: 1972
• Tongue: English
• Weight: 306 KB
• Volume: 12
• Category: Article
• ISSN: 0011-2275
• DOI: 10.1016/0011-2275(72)90004-5

✦ Synopsis

It is necessary to know the various properties of insulators at cryogenic temperatures in order to design cryogenic electrical devices. However, very little data are available at present because of the difficulties of making measurements. In this paper we report on preliminary measurements of the dielectric strength of some insulators for 50 cps ac voltage at room temperature, 80 K, and 20 K. Stone and McFee 1 measured the dielectric strength of some common electrical insulators in air at room temperature, in liquid nitrogen, and in liquid helium. In their measurements the expected improvement in dielectric strength at liquid helium temperature was not observed, and they made a conjecture that, in their tests, breakdown had been initiated by the liquid bath. One of the purposes of our experiment is to study if this conjecture is correct. Therefore, most of our tests were made in vacuum.

Device A

Eleven specimen films are sandwiched between twelve copper plane electrodes whose edges are surrounded by teflon rings, the resulting pile is then covered by teflon