Toshio Saitoh

Electromagnetic force and eddy current loss in dynamic behavior of a superconducting magnetically levitated vehicle

A magnetically levitated vehicle is being designed to travel between Tokyo and Osaka in about 1 h at a 500-km/h speed. When the car runs at a high speed, it moves laterally and vertically from its balanced position at low frequencies. The authors present calculations of electromagnetic forces and eddy currents generated in the onboard cryostat containing the superconducting magnet as a result of these motions. They show that the electromagnetic forces, eddy current losses and damping constants of the motion, especially for the lateral and vertical motions, depend on the materials of the radiation shield and the inner vessel in the magnet and change with the frequencies of car motion. The magnitudes of forces, losses, and damping constants in lateral motion are compared with those in vertical motion. To evaluate these quantities, numerical calculations were performed with a two-dimensional finite-element method.<<ETX>>

On-board power supply system of a magnetically levitated vehicle

A possible on-board power supply system for a magnetically levitated train is presented and its obtainable electrical power is estimated. The system uses special superconducting magnets, which are used only for generating electrical power. Some induction coils to pick up high-frequency components are set in front of the magnets. The special superconducting magnets and the induction coils will be mounted only at the head car and the tail car out of 14 cars in a train. The estimation shows that it is possible to obtain more than 630 kW of electrical power. >

Research and development of AC superconductors in super-GM

Abstract R&D of the superconductors (NbTi and Nb3Sn) for AC use has been conducted with theobject of their application to power apparatuses. As for three types of NbTi strands, values of hysteresis loss (Wh) divided by λ Jc were successfully reduced, and the lowest value consists of Wh of 11 J/m 3 (50 Hz, ± 0.5 T) and λ Jc of 2160 A/mm 2 (at 0.5T). Thus, AC 1 to 2 kA class NbTi conductors were developed. As for six types of Nb 3 Sn strands, the values were also reduced, and the lowest value consists of λ Jc of 2650 A/mm 2 (at 0.5 T) and Wh of 2300 J/m 3 (at ± 0.5T). The test coils wound with the Nb 3 Sn stranded wires allowed AC operation (50 Hz) more than 90% of lc on the load line. The data of these coils are greater than those of NbTi conductors.

Analysis for quench of superconducting magnets including the induced current effect

Abstract Quenching of a superconducting coil with metal vessels is affected by the induced current. A numerical calculational method in which vessels are treated as coils is used, taking account of the influence on the magnet generated by the induced current. The calculational results show that the profile of the superconducting current decay strongly depends on the helium vessels resistance. Furthermore, the temperature at the superconducting coil is lower as the resistance of the helium vessel is lower. Use of the helium vessel with low resistance is demonstrated as having an effect of delaying the time when the magnetic field begins to decrease.