World-Wide Benchmarking of ITER ${\rm Nb}_{3}{\rm Sn}$ Strand Test Facilities

Abstract

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> The world-wide procurement of <formula formulatype="inline"><tex Notation="TeX">${\rm Nb}_{3}{\rm Sn}$</tex></formula> and NbTi for the ITER superconducting magnet systems will involve eight to ten strand suppliers from six Domestic Agencies (DAs) on three continents. To ensure accurate and consistent measurement of the physical and superconducting properties of the composite strand, a strand test facility benchmarking effort was initiated in August 2008. The objectives of this effort are to assess and improve the superconducting strand test and sample preparation technologies at each DA and supplier, in preparation for the more than ten thousand samples that will be tested during ITER procurement. The present benchmarking includes tests for critical current <formula formulatype="inline"> <tex Notation="TeX">$(I_{\rm c})$</tex></formula>, <formula formulatype="inline"> <tex Notation="TeX">$n$</tex></formula>-index, hysteresis loss <formula formulatype="inline"> <tex Notation="TeX">$(Q_{\rm hys})$</tex></formula>, residual resistivity ratio <formula formulatype="inline"><tex Notation="TeX">$(RRR)$</tex></formula>, strand diameter, Cu fraction, twist pitch, twist direction, and metal plating thickness (Cr or Ni). </para>