Dr. Ulf Peter Trociewitz

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.

A superconducting electrical joint that links sections of Bi-2212 conductors. To establish high transport current carrying capabilities, Bi-2212 is heat treated at ~890°C and at elevated pressures. The heat treatment of the wire and the formation of the superconducting joints are carried out in the same heat treatment. To compensate for the pressure differential between the furnace and the inside of the wire (for Bi-2212 densification), the wires ends are sealed.  High pressure is applied to complete a full reaction process and ensure densification of the Bi-2212. 

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.