Tesla-Class Quasi-Persistent-Mode HTS Magnet Excited by Thermoelectric Element

A high-temperature superconducting (HTS) magnet excited by a thermoelectric element provided inside the magnet is being developed. An external power supply is not necessary for this magnet system to maintain an operating current. The magnet is expected to have some merits for systems using persistent-mode superconducting magnets, for example maglev trains. Advantages of the magnet system include its wide range of operating temperatures compared with low-temperature superconducting (LTS) persistent-mode magnets and its low weight compared with HTS persistent-mode magnets because its ability to use a smaller coil with higher load factor. The main components of the magnet system are a thermoelectric element, an HTS coil, and a cryocooler. The thermoelectric element is made of Bi₂Te₃ semiconductor and is cooled by the first stage of the cryocooler. The HTS coil is wound with Bi-2223 wires and cooled by the second stage of the cryocooler. A magnetic field of 1.82 T is produced with an operating current of about 125 A. This paper describes the design and experimental results of the magnet system.