Calculation of the critical current in pancake-coiled long length Bi-2223/Ag tapes in non-uniform local magnetic fields perpendicular to the grain alignment axis

摘要

The DC magnetic field pattern of three pancakewindings consisting of 150, 180 and 850 m of Bi-2223/Ag tape,was mapped within each winding volume. The analysis revealed avery non-uniform field distribution across the pancake widthwithin each turn of the pancake. The effect of this non-uniformfield across the tape width on the critical current of the pancakecoil and on short sections within a single turn was measured. Amodel is proposed to explain the observed experimental data alongwith a method for correctly calculating the field free critical current