Transport of cryogenic liquids or gases between installations at different electrical potentials

Two techniques are described to transport an electrically insulating cryogenic liquid or gas, typically liquid or supercritical helium between apparatus at different electrical potentials. The problem is solved in one case by applying high vacuum as simultaneous thermal and electrical insulation, and in the other case by using a potential controlled epoxy bushing as electrical insulator, installed in a cryostat which is thermally insulated in a conventional manner.