Cryogenic cooling apparatus with voltage isolation

Abstract

A cryogenic cooling apparatus (cryocooler) with voltage isolation includes a cold end structure, which may be placed in thermally and electrically conductive contact with an electrically charged structured to be cooled, a warm end, and an electrically insulating structure between the warm end and the cold end structure of the apparatus so as to electrically isolate the cold end structure from the warm end. Two cold fingers, each comprising a cold end structure, a warm end, and the insulating structure, may be conveniently combined into a single cooling apparatus for the cooling of two electrically charged structures at different voltage levels, e.g., conductive electrical leads to a cryogenic superconductive energy storage device. The electrically insulating structure is selected so as to provide both electrical isolation and to contain a cryogenic working fluid within the cold finger of the cryocooler. The cryogenic working fluid in the cold finger may be cooled by the use of a variety of thermodynamic cycle methods, including the Gifford-McMahon cycle, and a pulse-tube type cycle. For a Gifford-McMahon type cryocooler, the electrically conductive regenerator material located in a cold finger regenerator is interleaved with electrically insulating separators so that the local electric potential in the working fluid remains less than the breakdown voltage of the fluid as defined by Paschen's curve. The cold fingers may form the single stage of a cryogenic cooler or the terminal stages of a multi-stage cryogenic cooler.