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The world's largest pulsed superconducting coil was successfully tested by charging up to 13 T and 46 kA with a stored energy of 640 MJ. The ITER central solenoid (CS) model coil and CS insert coil were developed and fabricated through an international collaboration, and their cooldown and charging tests were successfully carried out by international test and operation teams. In pulsed charging tests, where the original goal was 0.4 T/s up to 13 T, the CS model coil and the CS insert coil achieved ramp rates to 13 T of 0.6 T/s and 1.2 T/s, respectively. In addition, the CS insert coil was charged and discharged 10 003 times in the 13 T background field of the CS model coil and no degradation of the operational temperature margin directly coming from this cyclic operation was observed. These test results fulfilled all the goals of CS model coil development by confirming the validity of the engineering design and demonstrating that the ITER coils can now be constructed with confidence.

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.

The latest achievements in the development of high performance Nb 3 Sn strands are reported. In the field of high energy physics (HEP) critical current densities up to 3000 A mm −2 (at 12 T, 4.2 K and 10 µV m −1 ) can be achieved. Current actions are aimed at reducing the filament size to about 50 µm and decreasing production costs by using less expensive base materials. In order to take advantage of the progress made by the HEP R&D program, the fusion community has initiated several strand procurement actions worldwide to produce advanced Nb 3 Sn strand types fulfilling the updated strand specification of the International Thermonuclear Experimental Reactor project. Recently developed internal-tin strands reach critical current densities of more than 1100 A mm −2 and acceptable non-Cu hysteresis losses of about 700 kJ m −3 . An important milestone towards higher production rate and yield was reached: a billet of about 100 kg was successfully drawn to the final strand diameter without problems. In powder-in-tube conductors, the composition and number of filaments have been modified to meet the European target specification. Although the bronze technique itself sets certain limitations on J c , strands with critical current densities around 800 A mm −2 have been produced on an industrial scale.