A." Nishimura

K. "Osamura

S. Awaji

National Institute for Fusion Science (NIFS-Repository)

Further, the local strain exerted on the SC layerwas investigated for the REBCO coatedconductors [2, 3].0.4Hitachi at R.T.0.50.40.1 0.2 0.3A(%)(a) Nb3SnA(%)0.8 ?-0.4o 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8-0.1???? 0.1Fig. 1 Cross section of practical SC strands,(left) Nb 3Sn and (right) Nb3Al.0.20.3(b) Nb3AlFig. 2 Applied strain dependence of total localstrain exerted on SC filaments.I)K. Osamura, S. Machiya, Y. Tsuchiya, H.Suzuki, T. Shobu, M. Sato, T. Hemmi, Y.Nunoya and S. Ochiai, Supercond. Sci. Technol.,25(2012)054010(9pp)2)K. Osamura, S. Machiya, Y. Tsuchiya, H.Suzuki, T. Shobu, M. Sato and S. Ochiai, IEEETrans. on Applied Superconductivity, 22 (2012)8400809(9pp)3) K. Osamura, S. Machiya, Y. Tsuchiya, S.Harjo, H. Suzuki, T. Shobu, K. Kiriyama, and M.Sugano, IEEE Trans. on AppliedSuperconductivitY,21 (201 I) 3090-3093Tn order to design the upgraded thermalfusion reactor, FFHR, the superconductingconductor and coil shall be used asindispensable key components. In practice,those superconducting devices will be exposedunder a huge magnetic force field. Therefore itis important to investigate their mechanical andelectromagnetic properties and to establish theirdiagnostic technology. With respect to thissubject, some typical results in this fiscal yearare reported here.Practical superconducting wires likeNb3Sn and Nb3Al strands and other HTS tapessubjected for fusion reactors are typicalcomposite material consisting of brittlesuperconducting component, oxide and metallicmaterials. Thermally induced strain generates inthe composite inevitably due to differentcoefficient of thermal expansion and differentelastic modulus among constituent components.It is necessary to evaluate its influences on bothsuperconducting and mechanical properties. Wehave carried out the systematic investigation tomeasure thermal strain and lattice one in severalpractical superconducting wires quantitativelyby means of quantum beam techniques. Thethermal strains along both parallel andtransverse to the strand are theoreticallyevaluated by the analytical manner. Fromcomparison of calculated results with theobserved values, the comprehensive calculationmethod has been established for Nb 3Sn andNb3AI strands and other HTS tapes.Figure 1 shows the cross section ofpractical SC strands. In case of Nb 3Sn strand,Nb3 Sn filaments are embedded in the Bronzematrix and surrounded by the Nb barrier andstabilized Cu components. In the Nb3AI strandfabricated by Jerry roll method, Nb3Al filamentsare embedded in the Cu matrix. Figure 2 showsthe applied strain dependence of local strainexerted on the SC filaments along the axial andtransverse directions. At the zero applied strain,the observed values give thermal strain. Thethermal strain for Nb3Sn strand is larger thanthat for Nb 3AI, while the lattice strain is similarfor both strands. The lattice strain is defined asthe increasing strain as a function of appliedstrain. The thermal strains along the axial andtransverse direction of strand have beentheoretically evaluated. The observed valueswere consistent with the calculated ones [I].223§24. Local Strain and its Influence on Mechanical - Electromagnetic Properties of Nb3Sn and Nb3Al StrandsOsamura, K. (RIAS), Awaji, S. (Tohoku Univ.),  Nishimura, A.

Local Strain and its Influence on Mechanical - Electromagnetic Properties of Nb3Sn and Nb3Al Strands

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