Speaker
Description
A 46 T all-superconducting magnet is being designed at the Institute of Plasma Physics Chinese Academy of Sciences. This magnet consists of, from the outside to the inside, the CFETR CS model coil capable of producing a 10 T central field, a REBCO-CORC insert coil providing an additional 10 T central field, and three REBCO insert coils which are dry wound with 4 mm wide REBa2Cu3O7-x tape conductors. First, the electromagnetic design is optimized by considering the central field, perpendicular field, hoop stress and strain, and conductor lengths. Then, special attention is paid to the screening current effect of the three REBCO insert coils. When the magnet is energised, persistent screening current will be induced in the winding. Subsequently, the non-uniform current distribution in the REBCO tape, including a varying-field induced screening current, will lead to critical magnetization effects that not only deteriorates the field strength, but also may overstress the conductor and result in irreversible degradation of the magnet performance. A code based on the T-A formulation is written to calculate the screening current effect. Meanwhile a finite-element software is also employed for comparison. We will focus on predicting and mitigating the screening current and its associated stress/strain in the 46 T magnet.
