AC Loss Analysis on a Quasi-Isotropic Strand Stacked by 2G Wires by Numerical Simulation in Cryogenic Temperature

This paper mainly presents an ac loss numerical study of quasi-isotropic strands fabricated by second generation wires in cryogenic temperatures of 4.2 and 77 K. In order to estimate the ac losses accurately, a scaling relation of critical current density depending on the magnetic field and magnetic field angle with wire is adopted in the model. AC loss contributions, including hysteresis and eddy current losses, are estimated in detail at 5-Hz magnetic field with amplitude range from 0.1 to 7 T. At low fields and 4.2 K temperature, hysteresis losses of quasi-isotropic strands are less than the eddy current losses (which mainly comes from the copper sheath), this situation is very different from the 77 K. Effects of the magnetic field frequency and orientation with a strand on ac losses are also particularly analyzed under different magnetic fields. The numerical results are helpful for overall understanding on ac loss characteristics of quasi-isotropic strands and are also useful for their applications in high magnetic field at low temperatures.