Two-dimensional quench simulation of composite CuNb/Nb_3Sn conductors

摘要

In order to clarify effect of utilizing a Nb rich CuNb reinforment on superconducting stability, r-z two-dimensional time-dependent numerical simulations on composite CuNb/Nb_3Sn wires are conducted. The time variations of temperature and current density distributions, minimum quench energy (MQE), and normal zone propagation velocity (v_p) of a Cu-17 vol percent Nb/Nb_3Sn wire, a Cu-63 vol percent Nb/Nb_3Sn wire, and a conventional Cu/Nb_3Sn wire are investigated. The increase of the volume fraction of an outermost Cu stabilizer provides high MQE but decreases the total current density. Although the v_p is not significantly influenced by the Nb fraction, the Nb rich CuNb reinforcement sacrifices the MQE for its high tensile strength. It is important for magnet design to control the volume fraction of the Cu stabilizer and Nb fraction in the CuNb reinforcement to balance the desired current density, tensile strength, and superconducting stability.