Aimant Supraconducteur à PArois Minces sur profil EXtrudé – ASPAMEX

This project aims at the development of a bulk superconducting material for electro-technical applications at the temperature of 77 K or lower. We are aiming more specifically to the use of bulk superconductors of the YBaCuO type as compact, even portable strong magnetic field (>2T) generator, in NMR device for instance . As a fact, as these bulk materials are cooled down in a magnetic field, they trapped and keep an ‘image’ of this activation field. As long as they are maintained at low temperature (€77K), they act as a permanent magnet. Hence, pellets of a few cm in diameter can provide ten Tesla or so at 40K. Using bulk superconductors enables the market segment opening of compact strong magnetic field generator (>2T) at a lower cost than conventional superconducting magnets. Various applications can profit by these materials as portable strong magnetic generators and have a potential market in the industry. Important developments are under way in Japan. The endorsed industrial applications are devices for magnetization, for controlling chemical reaction, for magnetic alignment, magnetic analysis, magnetic separation, as well as motors, generators, focalization devices of ion beam or magnetron sputtering cathodes in thin films technology. As far as material and process are concerned, this material offers numerous challenges. It has to have very high magnetic field trapping capabilities, and it has to sustain high mechanical and thermal stresses during its magnetic activation. To meet this application requirement, we aspire to develop a tailored material based on the original concept of thin-wall bulk YBCO single domains. This consists in growing a crystal on already shaped pellets presenting an array of holes, in such a way that the dimension of the walls remains below 2-3 mm. Advantages are numerous, among which we underline the followings: - The material can be handled as a standalone piece while benefiting of significantly reduced diffusion paths for its fabrication and implementation. - A better thermal homogeneity and a better gas exchange facilitate the crystal growth. - The thin-wall geometry combined with a high pressure oxygenation enables to significantly increase the functional properties of the material, with great time savings, using the same strategy directly applicable to any sample diameter. - Last but not least, this geometry enables the reinforcement of the mechanical properties and the material thermal stabilization, as well as its environmental resistance, by impregnation of the holes with a metallic alloy or a loaded epoxy resin. The complex shape of the thin-wall geometry is a technological barrier for developing the concept. Thin-wall geometries are not easy to fabricate. Machining or molding, with embedded needles, are dedicated to laboratory tests and small production. They are costly and limited solutions. However, similar shapes are industrially produced by extrusion as for instance the filters for catalytic exhaust systems. CTI SA is a specialist of such extuded honeycombs. The firts goal of this project is to apply this kind of technique to our raw material. We also hope to fabricate some more efficient geometries impossible to elaborate by machining or molding, notably with regards to the reduction of the holes diameter. We are confident that the outcome of the project will be a performing material tailored for the endorsed application. This material will outperform the existing standard bulk superconductors on the market while reducing processing time and hence the processing costs.