[1] UPMC, UPSud, Cent Supelec, Grp Elect Engn Paris GeePs,CNRS UMR 8507, Gif Sur Yvette, France
[2] Southwest Jiaotong Univ, State Key Lab Tract Power, Appl Superconduct Lab ASCLab, Chengdu 610031, Sichuan, Peoples R China
[3] Karlsruhe Inst Technol, Hermann von Helmholtz Pl 1, D-76344 Eggenstein Leopoldshafen, Germany