HTS CURRENT LEAD USING A COMPOSITE HEAT-PIPE

This paper discusses the design and fabrication of HTS current leads b eing built by Los Alamos to supply power to a demonstration HTS coil w hich will operate in a vacuum cooled by a cryocooler, Because vapor co oling is not an option for this application the leads must be entirely conductively cooled, In the design of HTS current leads for this type of application, it is desirable to intercept part of the heat load at an intermediate temperature, This thermal intercept or connection mus t be electrically insulating but thermally conductive, two mutually ex clusive properties of most candidate solid materials, To achieve this end we incorporate a composite nitrogen heat pipe, constructed of cond ucting and non-conducting materials, to provide efficient thermal comm unication and simultaneously, electrical isolation between the lead an d the intermediate temperature heat sink. Another important feature of the current lead design is the use of high Jc thick film superconduct ors deposited on a non-conducting substrate to reduce the conductive h eat leak through the lower portion of the lead. Two flexible electrica l conductors are incorporated to accommodate handling, assembly and th e dissimilar expansion coefficients of the various materials.