A 2 Tesla Full Scale High Performance Periodic Permanent Magnet Model for Attractive (228KN) and Repulsive Maglev

Two 214.5 cm long high performance periodic (26 cm period) permanent magnet halfassemblies were designed and constructed for use as a wiggler using Nd-B-Fe and vanadium permendur as hard and soft magnetic materials by Field Effects, a division of Intermagnetics General Corporation. Placing these assemblies in a supporting structure with a 2.1 cm pole to pole separation resulted in a periodic field with a maximum value of 2.04 T. This is believed to be the highest field ever achieved by this type of device. The attractive force between the two 602 kg magnet assemblies is 228 kN, providing enough force for suspension of a 45,500 kg vehicle. If used in an attractive maglev system with an appropriate flat iron rail, one assembly will generate the same force with a gap of 1.05 cm leading to a lift to weight ratio of 38.6, not including the vehicle attachment structure. This permanent magnet compares well with superconducting systems which have lift to weight ratios in the range of 5 to 10. This paper describes the magnet assemblies and their measured magnetic performance. The measured magnetic field and resulting attractive magnetic force have a negative spring characteristic. Appropriate control coils are necessary to provide stable operation. The estimated performance of the assemblies in a stable repulsive mode, with eddy currents in a conducting guideway, is also discussed. The development of this concept and overall configuration was internally funded by Intermagnetics. The design and construction of the permanent magnet assemblies was performed under a U.S. Department of Energy subcontract from the Stanford Synchrotron Radiation Laboratory (Stanford University Contract No. 7144.)