Superconducting Levitation by Stacked High‐Temperature Superconducting Tapes

Traditional magnetic levitation (maglev) demonstrates suspension of a bulk superconductor above a permanent magnet (PM), which is the principle for a high‐speed maglev train. This paper evaluates the possible reverse levitation of a PM vehicle on a stacked superconducting tape track following the reported concept of a multifunctional highway system. A variable number of stacked high‐temperature‐superconducting (HTS) tapes is used to elucidate an optimal trapped field on a minimum number of stacked tapes. At liquid nitrogen temperature, the surface remnant magnetic flux varies from 0.12 T for 5 tapes to 0.27 T for 121 tapes. Then a 1 m long vacuum cryostat with a stack of 29 tapes is designed and constructed. The cryostat is cooled down with a PM magnetizer of 0.80 T. On the cryostat, trapped fields of 90 mT at 77 K and 156 mT at 40 K are obtained, respectively. Although the remnant field in the tapes is low, the suitability for levitation and transport of a PM vehicle is demonstrated. The experimental study for the first time provides the special conditions and properties for suspending and floating a PM above an HTS tape stack as an important step toward the proposed multifunctional superhighway system.