HIGH-VOLTAGE INSULATION OF BINARY CURRENT LEADS

Binary current leads for liquid helium (LHe) cooled superconducting ap paratus offer a reduced amount of refrigeration power. The required in termediate cooling stage near the normal conducting part (NCP)-high cr itical temperature superconductor (I-ITS) interface needs special atte ntion when high voltages have to be maintained. Some principal ways ar e discussed. External cold nitrogen voltage breaks are found to be the most adequate solution. The benefits are discussed by means of an exa mple, and an evalution against conventional gas-cooled leads is given.