Very Large Engineering Critical Current Density Properties in a (6+1)-Structure MgB2 Superconducting Cable at 20 K. - Pan, Xi Feng; Yan, Guo; Cui, Li Jun; Li, Chao; Wang, Da You; Wang, Yu; Liu, Xiang Hong; Feng, Yong; Wang, Qing Yang; Zhang, Ping Xiang (IEEE Transactions on Applied Superconductivity, 2017)