Standardization of AC Loss Measurement of Cu/Nb-Ti Composites Exposed to Alternating Transverse Magnetic Field by Pickup Coil Method

Abstract

As the first step of a new standardization item of metallic superconductors in IEC/TC90- WG9, a round robin test (RRT) of AC loss measurement of Cu/Nb-Ti composite superconductors has been carried out by using the pickup coil method. Three kinds of Cu/NbTi multifilamentary wires were supplied and four laboratories participated in the RRT. The frequency dependence of AC loss was measured in an alternating transverse magnetic field with the amplitude of 1 T at 4.2 K in the frequency range between 0.005 Hz and 1 Hz. The hysteresis loss per cycle was obtained as an extrapolated level of the AC loss at f =0. The coupling loss was also obtained by subtracting the hysteresis loss from the total AC loss. From the RRT among the 4 laboratories, the coefficients of variation (COV) of hysteresis loss and coupling time constant were within about 5% and 10%, respectively. However, from the experimental results over a wide range of frequency in 3 laboratories, the COV was also reduced within 5% for the coupling time constant.