Levitation Coil Length Optimization of a Magnetically Levitated Train

Abstract

An experimental line of a magnetically levitated train (MAGLEV) using superconducting magnets (SCM) is now under construction in Yamanashi-Prefecture. In the MAGLEV system, levitation coils are mounted in side wall. Induced current of the levitation coils generates magnetic flux which include higher order harmonics. Those harmonics generate eddy current at the surface of the vacuum vessel of the SCM. Forces are produced by combining the eddy current and static magnetic field of the SCM. It causes evaporation of liquid helium, or SCM quench as the worst case. At present, the number of levitation coil layer is restricted to one. By removing the restriction, however, it is possible to reduce the amplitude of the harmonics of the magnetic flux. In this paper, the amounts of amplitude are studied by varing the levitation coil length, and it is found that there is an optimum length in which the amplitude becomes minimum.