Quench Protection for HTS Current Leads by Adding Connected HTS Bridges

Superconducting magnet systems operated at cryogenic temperature require high temperature superconducting (HTS) current leads to reduce the heat intrusion from the power supply at room temperature. However, some kinds of accidents, such as cryogenic failure, can cause a quench in the HTS current lead. Since the current conducting through the HTS current lead is very large, the quench in a HTS part can lead to a severe device failure. Therefore a study of a protection method for the HTS current lead is important. Generally, the HTS part of current lead used in large scale magnet systems has multiple separated HTS tape strands. They are electrically not connected or poorly connected. Therefore the quench in one strand affects other strands in current lead by applying additional loads for the other parts of the HTS current lead. In this paper, a strand-to-strand bridging method with HTS tapes is proposed as a quench protection method. Small scale HTS current leads with 2G HTS tapes and the suggested bridging method have been fabricated and tested.