Linear Motor Car Model Using a High-T_c Superconductor

Abstract

A linear motor car using the diamagnetism of a high T_c superconductor has been manufactured. In this model the track is constructed by Sm-Co permanent plate magnets magnetized perpendicularly to the plane. The car is comprised of Tl based superconductor with a critical temperature of 120K. When it is cooled by liquid nitrogen down to 77K, it becomes superconductive and levitates above the magnet track by the repulsive forces due to the diamagnetism. The levitating car moves smoothly along the track by applying traveling magnetic field by the propulsion coils which are layed at uniform intervals on the magnet track. According to 3-phase AC operation, the propulsion coils generate a traveling magnetic field and the car runs with the slip to the synchronous speed. As a results, we think that the driving mechanism is similar to induction motor. Because there are eddy current paths due to the grain boundary normalized in the superconductor.