Numerical evaluation of AC losses in an HTS insert coil for high field magnet during its energization

摘要

AC losses in a high temperature superconducting (HTS) insert coil for a 25-Tcryogen-free superconducting magnet are numerically calculated during itsenergization, assuming slab approximation. The HTS insert coil consists of 68single pancakes wound with coated conductors and generating a central magneticfield of 11.5 T, in addition to a contribution of 14.0 T from a set of lowtemperature superconducting (LTS) outsert coils. Both the HTS and LTS coils arecooled using cryocoolers, and energized simultaneously up to 25.5 T with aconstant ramp rate for 60 min. The influences of the magnitudes andorientations of the locally applied magnetic fields, magnetic interactionsbetween turns, and the transport currents flowing in the windings are takeninto account in the AC loss calculations. The locally applied fields areseparated into axial and radial components, and the individual contributions ofthese field components to the AC losses are summed simply to obtain the totallosses. The contribution of the axial field component to the total AC loss islarge at the early stages of the energization, whereas the total lossesmonotonically increase with time after the contribution of the radial fieldcomponent becomes sufficiently large.