Results of a New Generation of ITER TF Conductor Samples in SULTAN

Abstract

A new generation of ITER TF conductor samples has been assembled and tested in SULTAN in 2007 following a common procedure agreed among the ITER parties. The test results of six SULTAN samples, made of twelve conductor sections manufactured in Europe, Japan, Korea and Russia, are reported here. The conductor layout reflects the ITER TF conductor design, with minor differences for the Nb 3 Sn strand characteristics, void fraction and twist pitch. The object of the test is a straight comparison with the ITER requirement of 5.7 K current sharing temperature at 68 kA current and 11.3 T field. A broad range of behavior is observed.

Testing Large CICC in Short Sample Configuration and Predicting Their Performance in Large Magnets

“…Recent test results from one of a SULTAN sample, TFPRO-OST2 [7] with long twist pitches showed significantly lower degradation of that sample than similar cables with sharper twist pitches. It also showed a high N-value and low deviation from an exponential transition.…”

Qualification tests for ITER TF conductors in SULTAN

“…After the ITER Model Coil experience, the design of the TF conductors was adjusted in 2002 [7], but it was only in February 2007 till the first ITER TF conductor sample was tested in SULTAN [8]. In the following 16 months, till May 2008, nine samples, for a total of 18 conductors, were tested in SULTAN.…”

“…As long as the degradation is limited, say n ≥ 10, the slope of the electric field vs. temperature, dE/dT, at the criterion of 10 V/m is larger than 80 V/m K and voltage drift/offset as large as 2 V cause an very small error, <0.05 K, in the assessment of T cs . When dE/dT ≤ 15 V/m K, the accuracy of the T cs assessment is heavily affected by voltage drift/offset as small as 1 V. Moreover, in the large Nb 3 Sn samples of the last three years, the voltage drift observed at the end of the current ramp, before any raise of temperature has assumed new proportions, with values sometime above the criterion, and prevents a straight assessment of T cs from the raw data [17,8]. The large voltage drifts do not generate any measurable power, i.e.…”

“…An accurate measurement of the current sharing power by gas flow calorimetry has been used to benchmark the voltage post-processing procedure and is now integral part of the T cs assessment method [8,16].…”

Recent progress in a development of Nb3Sn internal tin strand for fusion application

“…It is well known that IT Nb 3 Sn strands are characterized by higher critical current capacity compared to bronze processed wires [1]. Therefore the advanced fusion reactors magnet systems rely mainly on the IT Nb 3 Sn superconductors with relatively high critical current and for ITER project the IT Nb 3 Sn strands for toroidal field coils and for Central solenoid will be supplied by the most manufactures from the participants countries [2].…”