Magnetic flux penetration and magnetization loss in a single REBCO tape exposed to full/positive-half non-sinusoidal perpendicular magnetic fields

High temperature superconducting (HTS) magnets are the core for an adiabatic demagnetization refrigerator (ADR). However, the local positive-half magnetic field at end windings introduces AC loss (termed as magnetization loss), resulting in thermal loads in the cryogenic system. Previous work mainly focused on the AC loss under full sinusoidal field waveforms, lacking systematic analysis on AC loss under positive-half field waveforms. Therefore, this work investigates the magnetization loss of a 4 mm HTS tape exposed to various full/positive-half sinusoidal and non-sinusoidal perpendicular magnetic fields, such as trapezoidal and triangular fields, to compare the influence of different field waveforms, field amplitudes and frequency on magnetization loss. Simulation shows that a higher ramping rate d B /d t only leads to higher magnetization loss at low- B and the magnetization loss almost overlaps at high- B due to fully penetration. The use of positive-half field waveforms can reduce magnetization loss by 80% at low- B in comparison with those under full field waveforms, this is due to the lower penetration depth. It is also found that magnetization loss under positive-half magnetic fields decreases with frequency as f -2/n at low- B and increases with f 1/n at high- B .