Thermal and Electromagnetic Performance Evaluation of REBCO Magnet With Solid Nitrogen Thermal Battery for Maglev Train

Researches on a magnetic levitation (maglev) train traveling in a vacuum tube have been actively conducted as a next generation ultra-high speed vehicle. For strong propulsion and levitation, a REBCO magnet is considered a feasible option. Due to the limited facility space of the maglev train, it has been proposed to eliminate the cumbersome cryogenic cooling system and power supply while the train is running. Applying a thermal battery instead of the on-board cooling system can suppress the temperature rise of the REBCO magnet while the maglev train is running. In this study, a solid nitrogen (SN ₂ ) is proposed as the thermal battery since it has a large sensible heat and an additional latent heat by α-β solid phase transition at 35.6 K. This can delay the temperature increase during the operating time. In addition, a semi-persistent current switch (semi-PCS) is applied with detachable current leads to operate the magnet without the power supply while the train is running. The detachable current leads can eliminate heat loss through the current leads. This paper describes the experimental results on the thermal and electromagnetic performance of REBCO magnet with the thermal battery after disconnecting the cooling system and the power supply.