Soldered double pancake winding of high temperature superconducting tape

Abstract

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 (critical current) degradation on kink points of the conductors, which is unavoidable. Soldered double pancake can be an alternative way to overcome the 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.Index Terms-Bobbin contact, contact resistance, HTS tape, soldered double pancake winding.

Progresses and challenges in the development of high-field solenoidal magnets based on RE123 coated conductors

“…The LW allows the entire coil to be wound with a single conductor piece, provided the conductor is long enough. In a DP coil, applicable to a high-aspect-ratio conductor, e.g., tape, two pancakes are wound sequentially, each pancake starting from the conductor midpoint and spiraling radially outward from the innermost to outermost turns [83]. The 'cross-over' form one pancake to the other at their innermost turns is continuous, i.e., no splice.…”

High-temperature superconducting undulator magnets

“…Because of their tape-shaped geometry, 2G-HTS do not tolerate significant side-bending, and this traditional approach of coil-winding is not feasible. Instead, HTS magnets are typically wound as pancake coils in which the tape is wound on itself from the inside out to the desired outer diameter of the magnet [20,21]. The connection between pancake coils is made through resistive bridge joints, and, depending on the coil geometry, there is one joint for every pancake coil [9,20] or for every two pancake coils [11,21].…”

The Integration of YBACU3O6+X Coated Conductors into Magnets and Rotating Machinery

“…There are indications, however, that the sideways bending of the innermost turn degrades the current-carrying capacity of the 1 st generation wires (Bi-2223) [10]. Making a conventional double pancake coil out of the 2 nd generation wire will prove to be even more problematic because of much higher rigidity of the flat metal tape with respect to the sideways bending.…”

“…The double pancake coils is a preferred form of making the field windings in rotating machinery because both ends of the coil are on the outside as opposed to a simple pancake coil [9]. There are indications, however, that the sideways bending of the innermost turn degrades the current-carrying capacity of the 1 st generation wires (Bi-2223) [10]. Making a conventional double pancake coil out of the 2 nd generation wire will prove to be even more problematic because of much higher rigidity of the flat metal tape with respect to the sideways bending.…”