Radial Resistance Estimation of Non-Insulated HTS Magnets

This paper presents an iterative method based on non-linear least squares for estimating the radial resistance of inductively coupled Non-insulated (NI) HTS coils. Although these results are of specific interest for levitated dipole fusion magnets, the estimation approach can be applied to any magnet composed of multiple NI HTS coils. OpenStar Technologies Ltd has developed a 5.6 T, 1.44 kA HTS magnet for a Levitated Dipole Reactor, named Junior, which consists of 14 individual NI coils. The proposed method was used to estimate the radial resistances in each of Junior's 14 coils, from multiple sets of experimental data. The results showed good agreement between the estimated parameters and experimental data. The largest estimated radial resistance for one coil was 3.93$\mu \Omega$. The smaller outer coils had the lowest estimated radial resistance, spanning from 360-770 n$\Omega$. Estimates were consistent across all considered datasets for all coils, with the exception of coils 1A and 2B.