Experimental and numerical study on AC loss reduction in a REBCO coil assembly by applying high saturation field powder-core flux diverters

Abstract

AC loss is one of the key issues need to be considered in designing high temperature superconducting (HTS) devices. An effective method for AC loss reduction is applying magnetic flux diverters (MFDs) in close proximity of the HTS coil windings. In this work, two types of low-loss powder-core MFDs − high flux (HF) and molypermalloy-powder (MPP) MFDs − were applied to a REBCO coil assembly for reducing the AC loss. The measured and simulated results show that both types of MFDs can significantly reduce the total loss (the summation of the losses in the HTS windings and the MFDs) in the coil assembly. At 77 K and 40 A coil current, compared with the coil assembly without MFDs, the total loss with HF and MPP MFDs was reduced by 77 % and 81 %, respectively. Although MPP MFDs show slightly better performance in reducing total loss in the coil assembly than HF MFDs at low coil current, HF MFDs are more obvious option for AC loss reduction in high magnetic field applications owing to their relatively high saturation magnetic field.