Feasibility of passive damping from mixed-mu levitation

Mixed-mu levitation is the principle whereby iron is levitated with respect to s magnetising coil and stabilised by the proximity of diamagnetic super-conduction screen material. For application to MAGLEV ground transport, superconducting coils and stabilising screens are mounted on on-board cryogenic levitator pads, the vehicle levitating about a mild steel rail. To obtain adequate ride characteristics, auxilliary damping is required and passive damping schemes, if feasible, are preferred to active control schemes. The paper investigates the feasibility of passive damping utilising a secondary suspension and primary system employing copper Sheets attached to the cryostat. A full dynamic model of the suspension system is presented together with model predictions and feasibility criteria.