The R&D Project of HTS Magnets for the Superconducting Maglev

This paper describes landmarks in the R&D project and the progress of persistent current HTS magnets, which has been in development for the Superconducting Maglev trains since 1999. The first trial HTS magnet is operated with a very small current decay rate of 0.44%/day and can be cooled by a cryocooler below 20 K, using a conduction cooling method. The HTS coil consists of 12 single-pancake coils that are wound with Ag-sheathed Bi2223 high-Je wires. The HTS coil is connected with a persistent current switch, and cooled by a pulse tube cryocooler. Detachable current leads are used to reduce heat leakage. The first magnet has been operated on the Central Japan Railway's Pavilion site of "The 2005 World Exposition," while the second HTS magnet for the actual Maglev vehicle on the Yamanashi Maglev Test Line has been manufactured making the most of the achievements in developing the first magnet. Practicability of the HTS magnet for the Superconducting Maglev will be verified by the running test