High-temperature superconducting (HTS) transformer-rectifier flux pump for powering no-insulation superconducting magnet with low characteristic resistance

No-Insulation (NI) superconducting magnets have gained much popularity since they have higher engineering current density and better stability. Charging an NI coil with a low characteristic resistance (R _c ), however, becomes problematic, because the low R _c limits the power supply voltage and make the charging extremely slow. Flux pumps can inject flux into closed high-T _c superconducting magnets without electrical contact, making it possible to maintain a quasi-constant field in the magnet with insignificant losses. In this paper, we propose and examine new methods to speed up charging the low R _c NI coil using a transformer-rectifier type flux pump. We will show that the flux pump has improved performance compared to an external power supply in charging the NI coil.