Magnetization AC Losses of Quasi-Isotropic Strand Stacked by 2G Wires at 77 K

Abstract

This paper numerically and experimentally investigates the magnetization ac losses in quasi-isotropic strand under external ac magnetic field at 77 K. The measurements of ac losses were carried out by the pick-up coil method in ac magnetic field at amplitudes from 0.03 to 0. 25 T and at frequencies between 20 and 100 Hz. Simulations made by a two-dimensional finite element method (FEM) model based on H -formulation were performed to predict the measured results. Because of the short length of sample and the existence of high transverse resistance between interwires in strand, the measured ac losses agree well with the simulation of magnetically uncoupled case. The coupling length of quasi-isotropic strand is found to be 1.422 m, based on the measured equivalent transverse resistivity of 1.342 mΩ·m. The full penetrated field of the strand at 77 K is 0.132 T, across which the frequency dependence of magnetization ac losses in strand becomes completely inversed. The systematic study on magnetization ac losses of quasi-isotropic strand could be the base for their applications in high field magnets.