A New Test Facility to Characterize React and Wind <formula formulatype="inline"><tex Notation="TeX">$ \hbox{MgB}_{2}$</tex></formula> Conductor

Abstract

A new test facility was developed at CEA/Saclay in collaboration with the SigmaPhi Company in order to perform studies of a dry MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> magnet operating at 10 K and medium range field (1 T up to 4 T). For a rapid use of the MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> conductors in an industrial product, notably in the medical sector, the “react and wind” technique must be used to wind magnets. However, the reacted MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> conductors have a minimum winding radius, classically around 100 mm, which is incompatible with the existing Saclay test facility. A new test facility has been constructed with a 600 A dc current power, a 300 mm diameter sample holder, and conduction cooling by a two-stage GM cryocooler. The background field for this test facility is provided by a NbTi coil, which has a warm bore of 350 mm and a maximum field of 3 T. This paper presents the design of this test facility, especially the design of the current leads, the insulated thermal contacts with the development of a new type of insulation based on aluminum nitride and the dry sample holder. Results of critical current tests in self-field are presented and compared with manufacturer data for a reacted MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> conductor, a Ni/MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> tape soldered on an OFHC copper stabilizer tape, supplied by Columbus Superconductors SpA.