Bending stress- and magnetic field-dependence of Ic in JFCA-RRT samples

Abstract Japan Fine Ceramics Association has carried out a round robin test (RRT) on the bending strain ( e b ) dependence of the critical current I c at 77 K in three kinds of Bi(2223)/Ag tape samples (VAM-1, JFC-1, JFC-2; three samples each) for future standardization. We measured I c ( e b ) ( e b : 0–1.0%) as one of RRT participants and also measured the magnetic field dependence of I c under several bending strains mentioned above as optional measurements. As results, we found a very fast decrease of I c in low fields up to 0.5 T and then a gradual decrease up to 1.5–2.0 T. I c maintains 0.9–0.95 of its initial value up to e b =0.4% strain and then decreases a little faster down to 0.60–0.65 at e b =1.0% for almost all samples and magnetic fields. The normalized pinning force F p /F p max shows scaling according to the expression F p /F p max ∝(B/B irr )(1−(B/B irr )) 3 for all samples and bending strains, where B irr is the irreversibility field.