Design of an Electric Joint Design to be Used in Electromagnetic Coils
The present invention describes an electric joint design to be used in electromagnetic coils made with high-temperature superconducting tape. The conductor runs without interruption all the way from the top of the coil along some part of the current lead and establish a distributed resistive joint outside of the area where the magnetic forces are high and helium gas may be trapped. One embodiment of this invention is to solder the conductor onto the complex contour that is machined into a terminal piece made from high purity copper. This contour allows for a change in the conductor direction by about 90 degrees as it leaves the winding pack just by applying a soft-bend and an internal twist without cutting it or forcing a hard-bend onto it.
Conventional resistive joints within the terminal region present a performance limiting factor in high field coil design. The problem solved by this invention is the avoidance of heat generating resistive joints in the terminals of coils made with high temperature superconducting tape cooled by liquid helium. These terminals are located at the coil ends in a region where heat dissipation can both generate and trap helium gas. The original liquid helium cooling of the joint becomes thus insufficient causing the coil to either not perform at its fullest potential or not maintain its superconducting properties and fail.