Nb3Sn Wire coil during manufacture.
The aim of developing ceramic electrical insulation is to study the implementation of insulation that can withstand the high-temperature heat treatment (600 to 700°C) required for the formation of certain superconductors, in particular those made of niobium-tin (Nb3Sn). The conductors are covered with fibreglass ribbon coated with precursors which react during the heat cycle, forming the insulation and ensuring the mechanical strength of the coil. In this way, two difficult stages of manufacture are eliminated: the handling of the reacted coil, which is very fragile, to remove it from the reaction mould and insert it into the impregnation mould, and the under vacuum impregnation stage with epoxy resin.
The work performed as part of Alexandre Puigségur's thesis made it possible to define the characteristics of the impregnation solution and showed that the use of this insulation did not affect the properties of the Nb3Sn strand. A small solenoid was successfully tested under strong external magnetic fields (12 T) in the department's Cétacé test facility and produced a self-field of 3.8 T with a transport current of 740 A.
A second superconductor winding in Nb3Sn (height 54 mm, external diameter 72 mm) with 400 turns was made, then tested in the Christiane test facility to assess the mechanical resistance of its insulation. Supplied with a current of 590 A, the demonstrator produced an induction of 5.6 T at its centre. By adding the magnetic field of the demonstrator to that generated by the Christiane magnet, we obtained a magnetic induction of 10 T at the centre of the system. No damage was observed in the study range (30 Mpa traction, 60 Mpa compression), and the transitions observed were systematically linked to the intrinsic performance of the Nb3Sn strand used.
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Dernière mise à jour : Jan 11th, 2024
