(1) Development of a Superconducting Magnet for the Simplified Ground Coil System
      Simplification of the ground coil system to be deployed on the guideway is under examination as a means of cost reduction, which is currently the biggest challenge in the technological development of the superconducting magnetically-levitated transportation system. For this purpose, the development of a superconducting magnet for the simplified ground coil system is required. The superconducting magnet must stay within the limit of the target weight, while demonstrating running vibration characteristics that satisfy the design standard vibration level and also ensuring that the heat in low temperature areas caused by vibration does not exceed the cooling capacity of the on-board refrigerator.
      An electromagnetic vibration test on the superconducting magnet simulating the simplified ground coil system and a mechanical vibration test of the superconducting coil were carried out (Fig.6). The results showed increased fluctuating magnetic fields and fluctuating forces on the superconducting magnet, and the following measures to improve performance have been proposed in response to these tests:
(1) Reduce vibrations on the inner vessel and piping by improving the rigidity of the outer vessel.
(2) Remove the resonance frequency of the whole superconducting magnet from the running speed area by improving the rigidity of the vertical load support.
(3) Reduce heat generation due to vibration by making strain generated in the superconducting coil uniform through strengthening the inner vessel of the load support member.

Fig.6 Superconducting magnet for the simplified ground coil

      The electromagnetic vibration test was conducted by improving the existing superconducting magnet as described above to verify these improvements. The test results verified that the preset requirements can be achieved. The performance improvement will be demonstrated in running tests on the Yamanashi Test Line.