Design and Development of a Pair of 10 kA HTS Current Leads for the NHMFL 45 Hybrid Magnet System

Abstract

During a planned replacement of one of the three superconducting coils in the outsert magnet of the 45 T Hybrid, there is an opportunity to replace the existing pair of standard helium-vapor-cooled current leads with a pair of leads incorporating high-temperature superconductor (HTS) sections. A conceptual design for these leads has been completed, and various critical components have been modeled and tested. The design includes an integral liquid-nitrogen reservoir at the interface between resistive and HTS sections, automatic liquid-nitrogen level control, a resistive heat-exchanger section cooled by nitrogen vapor, an HTS section with integral stainless-steel shunt for protection, and an interface to the low-temperature superconductor bus. A detailed design is presently underway and fabrication tooling and techniques are being developed. We present design details, projected performance, results of development testing, and plans for manufacturing and acceptance testing.

Binary Nitrogen-Cooled 10 kA Leads

“…In contrast, the Series Connected Hybrids are intended for use at maximum ramp rates on the order of 400 A/sec, so measurements at high ramp rates are included in the test protocol. Detailed design and early construction details are described in [4] and will not be repeated here. Additional features and later modifications are given in Section III.…”

Current-Lead Design for Cryocooled HTS Fault Current Limiters

“…One of the simple and effective ways to thermally protect the leads from an excessive current is to use a spiral roll-up of pierced metal sheet (called pierced "jelly-roll" or PJR) [15], as shown in Fig. 5.…”

R&D on 52-kA HTS Current Lead at ASIPP

“…In 2002-2004, the EU Fusion Development Programme, FZK, and CRPP successfully developed and tested a first 70-kA HTS current lead as a demonstrator for ITER [3]. In 2005, a pair of 10-kA HTS current leads was developed for the 45-T hybrid magnet system in the U.S. National High Magnetic Field Laboratory [4].…”