The Study of Critical Current for YBCO Tape in Distorted Bending Mode

Abstract

A mathematical model of equivalent bending radius was used to analyze the effect of bending strain on the critical current of yttrium barium copper oxide (YBCO) tapes in distorted bending mode. The relationship between critical current and twist pitch under different bending radii was measured. For enough larger twist pitch, even though the bending radius was smaller than the critical bending radius, the equivalent bending radius was always greater than the critical bending radius. Only when the bending radius was less than the critical bending radius and the twist pitch was reduced to a certain extent, the equivalent bending radius was smaller than the critical bending radius. As a consequence, the critical current dropped sharply and cannot be restored. The model and analytical equation was feasible and can be used for the design of solenoid YBCO magnet.