Soldered double pancake winding of high temperature superconducting tape

To make a superconducting coil by winding a High Temperature Superconductor (HTS) tape conductor on a bobbin, the double pancake winding technique is widely used to reduce number of splicing contacts between conductor pieces. However, this makes some Ic (critical current) degradation on kink points of the conductors, which is unavoidable. Soldered double pancake can be an alternative way to overcome the Ic degradation. This paper describes and compares the two ways of winding; usual double pancake, and soldered double pancake. Characteristics of the windings are measured and compared. The soldered double pancake winding has resistance on the contact points, but the estimated Joule heating on the contacts is much smaller than heat leak of cryostats.