A 30 kJ Bi2223 High Temperature Superconducting Magnet for SMES with Solid-Nitrogen Protection

A conduction-cooled high temperature superconducting (HTS) magnet system through a solid nitrogen protection with energy storage of 30 kJ was developed. The HTS magnet system is used to investigate fast discharging performances with a constant output voltage. The superconducting magnet consists of 14 double pancakes wound with Bi2223 tape with the length of 200 m. The magnet has an outer diameter of 212 mm and a clear bore of 108 mm. Cryostat for the HTS magnet system is designed and the coil is cooled with a GM cryocooler together with the solid nitrogen protection technology. The superconducting magnet is fabricated and tested. The operating current is about 155 A with raping rate of 5 A/s. It can generate a central magnetic field of 4.31 T at a temperature lower than 20 K. In this paper, the magnet design, coil fabrication and cryogenic system are presented. Experimental research of the superconducting magnet as a constant voltage power supply was carried out.