Effects of impregnating material failure on stability of superconducting magnet analyzed by wire dynamics simulation

The wire dynamics simulation has been performed to evaluate the stability of the impregnated superconducting magnet. The relationship between quench current and the impregnating material failure in the superconducting magnet was studied. In the impregnated superconducting magnet it is considered that the heating is induced by the cracking of the impregnating material or by the friction between wire and wire or wire and bobbin after the cracking. The wire dynamics simulation developed in this study can clarify the behavior of a superconducting coil by solving the equation of motion for each wire with time. In this simulation impregnating material was simulated as springs which connect between wires. The stresses to the springs were calculated, and were used to decide the failure of the impregnating material. It was found that just after the impregnating material cracking the heating increased suddenly at the place where the cracking of the impregnating material was induced and results in quench. The sudden increase of heating was caused by friction between wire and bobbin. This result suggests that the impregnating material failure is closely related to the stability of superconducting magnet.