Superconducting stack brazing method and mold for high-temperature superconducting current leads

Abstract

The invention discloses a superconducting stack brazing method and a mold for high-temperature superconducting current leads. The superconducting strips to be welded and the brazing welding strips are alternately put into a mold cavity made of a metal material with good thermal conductivity. The mold core and counterweight are pressed on the superconducting tape. Under vacuum conditions, the mold is heated to the brazing temperature and kept for 10-15 minutes, and then the mold is rapidly cooled to the solidification point of the brazing material to complete the welding. The critical current of the high-temperature superconducting tape with low thermal conductivity is only 100-120A under the self-field of 77K, which is much smaller than the operating current of thousands to tens of thousands of amperes of large superconducting magnets. The superconducting tapes must be welded and stacked for use. The price of the bismuth-based superconducting tape using Ag-5.3wt.% Au alloy as the matrix is ​​5-6 times that of the ordinary bismuth-based superconducting tape; and the price of the superconducting stack of foreign high-temperature superconducting companies is almost doubled. The method of the invention welds the superconducting stack with the mold, which can ensure that the current-carrying performance will not be degraded, the longitudinal heat leakage will not be increased, the welding between the superconducting strips is even, and the performance requirement of low interlayer resistance can be met.

Description

Technical field: [0001] The invention relates to a high temperature superconducting current lead stack brazing method and a mold for a large superconducting magnet. Background technique: [0002] In the 21st century, China will apply superconducting technology to high-energy accelerators, nuclear fusion experimental devices, high-field magnets and energy storage magnets on a large scale. The difficulty and high operating costs of 4K low-temperature refrigeration technology have hindered the application of low-temperature superconductivity, in which the current leads feeding large superconducting magnets are the most important heat load. The use of high temperature superconducting (HTS) current leads can reduce the 4.5K thermal load by an order of magnitude. High-temperature superconducting current leads for small superconducting magnets are commercially available, but high-current leads need to be made by themselves with low thermal conductivity Bi-2223 tape. [0003] For ...

AI Technical Summary

Problems solved by technology

Unlike the niobium-titanium alloy-based low-temperature superconducting materials with excellent mechanical properties, HTS ribbons are very fragile, and excessive bending or kink will lead to loss of superconductivity

In other words, if you accidentally lose part of the superconducting tape during the fabrication and brazing of the superconducting stack, it will cause significant economic losses.

Images