Limiting current-carrying capacity of YBCO superconducting tape at 30T
ROMANOVSKII Vladimir, 渡辺 和雄, 淡路 智, 西島 元, 松尾 浩幸 （東北大）
kwata*imr.tohoku.ac.jp
Abstract:Current stability analysis of IBAD-PLD YBCO coated tape with copper and silver stabilizing layers cooled by liquid helium are performed at 30 T for B//c. Under this cooling condition, the stable current modes of a superconducting composite are limited by the jump transition from the nucleate to the film boiling regimes. Such instability conditions were studied using static zero-dimensional model when the thickness of a copper layer was varied in the wide range. It is shown that the instability current increases practically linear with increasing the copper thickness. Current-sharing analysis depicts that this current-carrying capacity variation is due to the corresponding increase of the current stably flowing in the copper layer. Moreover, the calculations indicate the existence of the stable sharing current, which is about 0.7 A per 1 micron copper layer thickness at 30 T. For instance, the tape with 100 microns thick copper layer enables us to use the stable current-carrying capacity up to about 340 A, even when the critical current of the YBCO core is 172 A at 30 T and 4.2 K. However, in the case under consideration， the total heat release in the tape is not significantly change. As a result, the stable current sharing may occur below about 40% up of the critical current of the YBCO core at 30 T for B//c.