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Torsion dependence of the critical current in a superconducting Nb3Sn wire: modeling versus experiment

Baar, M.L.R. van den (2013) Torsion dependence of the critical current in a superconducting Nb3Sn wire: modeling versus experiment.

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Abstract:In large magnets, mechanical forces on the wire rise very high. These forces may degrade the superconducting performance of the wire. The impact of the forces depends on the wire structure. Extensive research has been done on axial and transverse deformations of single strands, but not on torsional deformation. The research in this thesis is an addition to the understanding of the strain sensitivity of the critical current in superconducting Nb3Sn. The first result of the effect of torsion on a Nb3Sn bronze route strand is obtained in parallel magnetic field at the Energy, Materials and Systems group at the University of Twente. The critical currents are measured between an angle of twist of 120° and 840°. Several models have been proposed to calculate the critical current via the scaling law of A. Godeke. To model the effect of the parallel magnetic field, the output of the scaling law was scaled via Schild’s magnetic field orientation dependence. The strains used in this thesis were obtained from a three-dimensional FEM model in COMSOL. Eventually it is concluded that the principal strains should be inserted in the deviatoric strain, which must be used in the scaling law. A rescaling of the law is still necessary and the performance of the three dimensional scaling law should be validated by a detailed mechanical analysis.
Item Type:Essay (Bachelor)
Faculty:TNW: Science and Technology
Subject:33 physics
Programme:Applied Physics BSc (56962)
Link to this item:http://purl.utwente.nl/essays/63677
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