Analysis of Current Distribution in Bi-2223/Ag Insert Pancake Coil

Abstract

A Bi-2223/Ag insert was fabricated to assemble a high field superconducting magnet. The insert consists of 17 double pancakes, with turn to turn and layer to layer insulations. To get the current distribution in each turn of the pancake coil, a numerical method of magnetization in a thin film derived from E.Zeldov was employed. To improve the calculation accuracy, we add the I C data tested from the experiments into the code directly. In the calculation, we take several different cases into account, such as High Field-Low Current (HFLC) case, Low Field-High Current (LFHC) case, which will have an effect on the current distributions. The overall process is divided into three sections: Firstly, we calculate the nonuniform but symmetrical transport current distributions through the transport current model. Secondly, the non-uniform and asymmetrical transport current distributions is recalculated through the magnetic field and transport current model. Thirdly, the screening current distributions are calculated after the coil is discharged.