The effect of the wire design parameters on the stability ofMgB2 superconducting coils

Abstract

The thermal stability of superconducting wires is one of the importantissues for wire applications. We present a numerical study on the effectof the wire design parameters on the quench behavior of superconductingMgB2 wire employed in coils. The model considers a stack ofMgB2 wires of rectangular cross section separated by insulation layers and subjected to a thermaldisturbance. The problem is solved on a two-dimensional domain and employs the currentsharing concept in the transition between superconducting and normal states. The effectsof three design parameters in wire manufacturing are investigated. Quench behavior iscompared for wires having different filling factor of superconducting filaments, differentvolume of copper stabilizer, and different residual resistivity ratio (RRR) valuesfor copper. The results indicate that the quench propagation velocity (QPV) at1.5 T is weakly affected by changes in the volume and electrical properties ofcopper, whereas the minimum quench energy (MQE) is strongly dependent on theRRR value of copper and can increase by a factor of nearly 2 with the RRRvarying from 30 to 150. Both the MQE and QPV change remarkably by varying theMgB2 filling factor. The MQE drops by a factor of 6 and the QPV increases by a factor of 2 withthe filling factor varying from 10.5% to 25%.