Sviluppo e caratterizzazione di bulk superconduttori in MgB2 per sistemi di levitazione

A complet analysis about the superconduction levitaton forces of various MgB2 samples has been performed as preliminary study for an innovative linear levitating system. MgB2 bulks are produced by the Reactive Liquid Infiltration (Mg-RLI) method developed by Edison SpA. The experimental results are also evaluated by means of numerical models. A new measurement system have been developed to perform an evaluation of the levitation forces of three MgB2 bulks as case study: a disc, a cylinder and a slab. The possibility to joint different pieces of bulk has been proved, such as the optimal relaxation time of this material (S=0.009 @ 33K). A numerical model has been developed to evaluate the experimental results of the MgB2 disc and to investigate the electrodynamics of levitation. Several types of permant magnets (PM) configuration have been coupled with a MgB2 cylinder to tentatively determine the best configuration; that has been also numerical evaluated by means of a numerical model which take into account the number of the PMs and the presence of rings of magnetic material between them to form a rotor. Similar studies has been carried out on a planar geometry by a MgB2 slab and different PM configuration. An innovative refrigeration method based on solid nitrogen has been studied to be coupled with a levitation system. The cryostat consists of two nested dewars, built by differents materials; the internal one lodge four MgB2 slabs while the external one reduce the thermal losses. A guideway made of NdFeB permanent magnets has been realized to test in Field Cooling configuration the possibility to use MgB2 †" RLI for levitating systems.