YBaCuO current lead for liquid helium temperature applications

A study was made of the losses of a double current lead (copper from 300 K to 77 K and YBaCuO from 77 K to 4.2 K). The authors give the main results obtained: (1) on the value of 1/J/sub c/ integral /sub 4.2/ /sub K//sup 77/ /sup K/KdT, (2) on the electrical contact resistance between YBaCuO and metal, (3) on the transport critical current density and 50-Hz losses of sintered tubes and textured material, and (4) on a 1-kA double DC current lead. On the basis of these results, it seems possible to decrease the current lead losses by a factor of 5.