Numerical Study on Thermal Stability of No-Insulation Coils Using a Three-Dimensional Finite-Element Model

No-insulation (NI) coils possessing maximized volume current and quench recovery ability have become one of the most promising technologies for high-field high-temperature superconducting windings. In this article, we constructed a complete 3-D finite element model incorporated with the circuit and heat modules that allows a detailed simulation on the transportation behaviors of the NI coils. Critical problems including the circulating and radial electro-magnetic transportation behaviors during the excitation process with different ramping rates; the thermal propagation in the overcurrent circumstance and related quench protection; and the effect of parallel winding of stainless steel tapes have been investigated using the newly proposed model. A detailed comparison of NI and metal-insulated coils on thermal stability and quench recovery ability with the presence of hot spots has been implemented. Such a 3-D model enables a close look at the electrical and magnetic field distribution, and predicts more accurate coil-parameters for the circuit model where detailed material properties can as well be included.