Study on Terminal Joint Resistance and Current Distribution in Parallel-Wound HTS Coil

The joint is one of the core components of high temperature superconducting (HTS) magnet, responsible for enabling the current transmission, and it is a key factor in evaluating the performance of HTS magnets. HTS parallel-wound (PW) coils, formed by parallelly stacking tapes, have been minimally studied in terms of joint manufacturing and measurement. The current shunting introduced by joints is one of the important parameters affecting the electrothermal performance of PW coils. This study investigates two manufacturing methods suitable for joints of PW coil and measures each joint resistance between HTS tape and copper terminal. The current distribution and heat loss caused by joint are analyzed by testing and simulation. The results indicate that the joint-distributed method is the preferred solution for manufacturing multi-joint connections on the same terminal. A 3-tape PW coil is wound using this method for both inner and outer joints. Further analysis shows that greater non-uniformity in joint resistance results in a more uneven current distribution among parallel tapes and increased heat generation during steady-state operation. The addition of parallel tape-to-tape shunt can reduce losses, especially during high current operation.