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University of Technology of Compiègne, France

Bruzzone P.,EPFL CRPP | Wesche R.,EPFL CRPP | Cau F.,EPFL CRPP
IEEE Transactions on Applied Superconductivity | Year: 2010

The change of length upon heat treatment of steel jacketed, Nb 3Sn cable-in-conduit conductors (CICC) is driven by the difference of coefficient of thermal expansion between Nb3Sn and the other components. The cold work of the steel jacket also plays an important role. During the preparation of CICC samples for test in the SULTAN facility, the change in length has been systematically measured for 16 sections of CICC. The broad range of changes, from elongation to shrinkage, is a concern for the manufacture of the ITER toroidal field (TF) coils, where the shape/length of the conductor after heat treatment must be exactly predicted to fit into the radial plates. For a reliable assessment of the performance of Nb3Sn CICC, the axial, thermal strain in the Nb3Sn filaments is a key parameter. To gain information on the subject, the residual strain on the steel jacket is systematically measured by strain gauges on 28 ITER CICC sections tested in SULTAN. The range of results is very broad and no clear correlation is found with the conductor performance, i.e. with the thermal strain in the filaments. To gain more inside about the actual thermal strain in the Nb3Sn filaments embedded in a CICC, neutron diffraction techniques have been applied (with limited success) to deduce the thermal strain from the direct, in situ measurements of the lattice parameter. © 2006 IEEE.

Bruzzone P.,EPFL CRPP | Stepanov B.,EPFL CRPP | Wesche R.,EPFL CRPP | Bagnasco M.,EPFL CRPP | And 7 more authors.
IEEE Transactions on Applied Superconductivity | Year: 2010

One year of operation and test activity of the SULTAN test facility at CRPP-Villigen, from October 2008 to October 2009 is reviewed. The main improvements of the facility include a new control system for the cryo-plant and a new electric motor for the helium compressor. The range of operation for the SULTAN samples has been improved in terms of cyclic loading rate. The test campaigns from October 2008 to October 2009 include eight ITER TF conductor samples, two JT60SA samples and a number of other developmental samples. The highlights of the test campaign and the statistical data about cool-downs, warm-ups and test duration are reported. For the eight ITER TF samples, more detail is given about the joint development, the standard test program and the data reduction for the assessment of the results. Eventually, an outlook in the next operation period is also discussed. © 2006 IEEE.

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