27 August 2017 to 1 September 2017
RAI Congress Center, Amsterdam, The Netherlands
Europe/Amsterdam timezone

Evaluation of thermal strain induced on components of Nb3Sn strand during cool down

28 Aug 2017, 13:15
1h 45m
Posters Area

Posters Area

Poster Presentation of 1h45m F1 - Low-Tc Wires and Cables Mon-Af-Po1.08

Speaker

Mr Tomone Suwa (National Institutes for Quantum and Radiological Science and Technology)

Description

Practical Nb3Sn superconductive strands of composite material were utilized for a cable-in-conduit conductor (CICC) for ITER central solenoid (CS) which consist of 576 Nb3Sn strands, 288 Cu strands and a stainless-steel jacket. During the manufacture of CS, heat treatment up to 923 K is applied to the CICC for reaction of Sn and Nb in Nb3Sn strands. the CICC is cooled down to approximately 4 K to operate ITER magnets. Thermal strain on Nb3Sn filaments of the strand is induced by large temperature difference and different coefficients of thermal expansion among components of the strands and the jacket. Strain dependence of critical current, which is used for prediction of the conductor performance, is influenced by thermal strain. Therefore, it is important to understand mechanism of the inducing thermal strain on the Nb3Sn filament. To distinguish contributions of the Nb3Sn strand components and the jacket to thermal strain on Nb3Sn filaments, internal strain measurement of the Nb3Sn strand was carried out by using neutron diffraction during cool down from 300 K to 12 K. As the results of the measurement, it was found that compressive thermal strain on Nb3Sn filaments was -0.1% at 300 K and -0.2% at 12 K in axial direction. In this paper, stress-strain state of components of the Nb3Sn strand during cooldown is discussed.
Acknowledgement: We acknowledge the support of the Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, in providing the neutron research facilities used in this work.

Submitters Country Japan

Primary author

Mr Tomone Suwa (National Institutes for Quantum and Radiological Science and Technology)

Co-authors

Dr Tsutomu Hemmi (National Institutes for Quantum and Radiological Science and Technology) Toru Saito (QST) Dr Yoshikazu Takahashi (National Institutes for Quantum and Radiological Science and Technology) Dr Takaaki Isono (QST) Dr Vladimir Luzin (Australian Nuclear Science and Technology Organization) Dr Hiroshi Suzuki (Japan Atomic Energy Agency) Dr Stefanus Harjo (JAEA)

Presentation Materials