For REBCO magnets, the no-insulation (NI) winding technique, which eliminates turn-to-turn insulation, is considered a key approach. The NI technique offers advantages, particularly during quench events, as the absence of turn-to-turn insulation allows current to bypass localized heat sources or defects naturally. In fact, several studies have reported that NI magnets achieved higher operating...
This paper presents both numerical and experimental investigations aimed at achieving accurate measurements of critical current in no-insulation (NI) high-temperature superconducting (HTS) coils. Leakage currents can flow through the turn-to-turn contact resistance in NI HTS coils. Additionally, screening current-induced voltages become dominant factors during the initial charging process....
No-insulation (NI) high-temperature superconducting (HTS) coils have gained attention for their high overall current density, thermal stability, and mechanical integrity. However, the time constant and the characteristic resistance in NI HTS coils, which are dominantly governed by radial turn-to-turn contact resistances, still require further investigation to examine coil specifications....
To generate the twisted magnetic fields necessary for fusion plasma confinement, stellarators have historically required complex and precise modular coils, which are difficult to manufacture and maintain. In mitigating this challenge, Thea Energy, Inc. is actively developing “Eos”, a planar coil stellarator that can shape the needed magnetic fields using arrays of hundreds of smaller,...
In the development of high-temperature superconductor (HTS) pancake coils, the no-insulation (NI) is a well-known approach that enables self-protection by allowing radial current redistribution during thermal events. This method, while advantageous for mitigating damage during quench, presents significant challenges due to the low contact resistance, which causes a substantial reduction in the...
High-temperature superconductor (HTS) coated conductors (CC) can be wound into no-insulation (NI) pancake coils, i.e., coils without electrical insulation in-between the turns. Along the CC length, the critical current has an inherent variation due to its manufacturing process. This variation causes non-uniform heat generation when the coil is operated at a high fraction of the critical...
The no-insulation (NI) winding method is widely known for its ability to improve the stability of high-temperature superconductor (HTS) coils by bypassing the hot spot during a local quench. However, one major drawback of this method is the occurrence of charge and discharge delays due to current leakage between winding turns. To address this limitation, we recently proposed an impregnation...
The contact resistance of non-insulation high-temperature superconducting (NI HTS) coils is an important parameter to characterize their thermal stability. While numerous discharging experiments have demonstrated that the contact resistance of NI HTS coils is not constant, the real-time evaluation of its transient behavior remains insufficiently explored. This paper proposes a novel inverse...
For non-insulated (NI) HTS coils wound with thin REBCO tapes, on the one hand, due to increasing current density, the coils can generate higher magnetic field; on the other hand, the compactness and the mechanical stability of the coils can be improved for the reason of higher proportion of Hastelloy. However, up to now, there is a lack of experimental research data on the electro-thermal...
