Performance of Japanese $\hbox{Nb}_{3}\hbox{Sn}$ Conductors for ITER Toroidal Field Coils

Abstract

The Nb 3 Sn cable-in-conduit conductors for the ITER TF coils are fabricated using the latest high performance strands. The strands made by bronze and internal-tin methods are used for the conductors with a void fraction of 29% and 33%, respectively. Superconducting performance of the conductors was measured at the operating condition of the TF coils. The measured current sharing temperatures Tcs are 6.3-6.6 K for the bronze and 5.6-6.1 K for the internal-tin. The Tcs of the conductor with void fraction of 29% is 0.1-0.3 K higher than the conductor with a void fraction of 33%. It is shown from the results that the strain on the cable is between 0.7% and 0.75% and the n-values are between 4 and 6, much smaller than the n-values of strands.Index Terms-Current sharing temperature, ITER, Nb 3 Sn CICC, SULTAN, toroidal field coil.

Technology development and mass production of Nb3Sn conductors for ITER toroidal field coils in Japan

“…JAEA has performed tests on two conductor samples with strands manufactured by two different suppliers. The results demonstrate that both conductors possess a sufficient temperature margin [30,31], thereby meeting ITER requirements. Both the strands and cable must be manufactured in a manner identical to that of the full-size conductors subjected to testing.…”

Numerical analysis on the current-sharing temperature of LTS/HTS hybrid conductor

“…Currentsharing temperature is commonly defined as the temperature at which the voltage along the conductor reaches a threshold value defined by the critical electric field of 0.1 V/cm [5,6]. By solving above equations numerically, the [7], then the field along conductor can be figured out (n H =15, n L =25 are used in all the following calculations).…”

Qualification tests for ITER TF conductors in SULTAN

“…They are made from strands supplied by nine different companies in five DA's, four of them using bronze and the others "internal Sn" technique for the Nb 3 Sn strand assembly. More detail about the conductor layouts can be found in [10][11][12][13][14][15].…”