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In the framework of the RD - one strand manufactured by Alstom (France), with a CuNi barrier and 0.81 mm diameter; - one strand manufactured by Bochvar VNIINM (Russia), Ni plated and 0.73 mm diameter. An extensive test campaign has been performed at GHMFL (CNRS, Grenoble) in 2003 using the CEA VTC facility at temperatures ranging from 4.2 K to 7.5 K and at magnetic fields ranging from 2.5 to 10.5 T. The results showed that all three strands have quite close performances in the ITER PFC operating range despite their structural differences and that due to the critical current density curvature with temperature, they fail to meet the 1.5 K PFC temperature margin criterion by 0.2 to 0.3 K. Additionally, applications of corresponding fits to PF-FSJS tests showed consistent results and finally a brief discussion on fitting formula is presented.

The JOSEFA (joint subsize experiment facility) experimental test facility, installed at CEA/Cadarache is devoted to perform tests at cryogenic temperature on subsize superconducting conductor and joint samples under parallel or transverse magnetic field. This facility was built in 1993 to investigate the performances of joints of cable-in-conduit conductors at subsize level and further upgraded in the framework of European tasks. The samples of hairpin type using subsize ITER conductors are cooled by a circulation of supercritical helium in a temperature range from 5 to 15 K and tested at a maximum current up to 10 kA. Two different helium bath cooled magnets allow to apply DC or AC transverse magnetic field up to 3.5 T or longitudinal magnetic field up to 7.5 T. A sliding system with a 240 mm stroke on the sample cryostat allows to test separately in the same sample either the conductor or the joint performances. The paper reports on how, through the conductor and joint development tasks, the facility performances were successfully increased and tested. The ITER TFMC joints using Nb/sub 3/Sn conductors were first developed on this facility. The last developments, performed on the ITER PF NbTi conductors and joints proved this facility to be a versatile and useful tool for superconducting magnet developments and showed the interest of possible upgrading to finalize conductor design.

In the framework of design and development of the International Thermonuclear Experimental Reactor (ITER) Toroidal Field (TF) Coils, a 45 m conductor winding has been manufactured by the Russian Home Team: the Toroidal Field Coil Insert (TFCI). It was tested in the JAERI facility (Naka, Japan) under various field and temperature conditions. The work presented here concerns the analysis of the electromagnetic behavior of the TFCI using a model developed at CEA. Our work focuses in particular on all observations related to voltage variation with temperature: current sharing temperature (T/sub CS/), n-value, and modeled strand behavior inside conductor.

The ITER Toroidal Field Model Coil (TFMC) was tested in 2001 at FZK (Karlsruhe, Germany). The BB1 busbars were instrumented with Hall probes to measure the current distribution across their cable sections. The BB1 busbars are pieces of conductor, about 7 m long, connecting the coil terminals to the BB2 busbars (going to the current leads). The cable is composed of 1152 twisted NbTi strands grouped into six main subcables (petals), each wrapped with a steel foil. The experimental setup is described as well as the method used for calculating the current distribution which leads to estimate the current unbalance among the petals. We observed a slight but monotonous evolution of the steady current distribution as current increases. We also analyzed the transient evolution between inductively and resistively driven current distributions, during a current plateau following a ramp. Assuming the inductive distribution to be uniform, leads finally to a low absolute nonuniformity (within /spl plusmn/6%) of the steady current distribution among the petals. The transient behavior is also discussed through a simple theoretical model.

In the framework of the design and the development of the ITER PF coils, two subsize joint samples (scale /spl sim/1/6) made of two different NbTi strands were manufactured at CEA/Cadarache (France) and were tested in the JOSEFA test facility at CEA. The characterization of joints was achieved in the areas of resistance T/sub CS/, pulsed field losses, and thermodynamic stability. The experimental results were interpreted with regard to the ITER specifications.

2/spl times/3.5 /spl mu/m thick Bi 2212 tapes have been prepared by oxidation reaction of precursors deposited electrolytically in a sequential way on both sides of a 50 /spl mu/m thick Ag tape. To try and increase their critical current density MgO doping was attempted. For the sake of making the comparison as differential as possible a sample of Bi 2212 precursors was prepared by electrodeposition. Part of it was directly heat treated, whereas the left was electrolytically plated before with MgO to get the average composition Bi/sub 2/Sr/sub 2/Ca/sub 1/Cu/sub 2/Mg/sub 0.1/. It was found that the transport J/sub c/ at 4.2 K of the MgO-doped specimen was about 1.4 times higher than that of the other in self field conditions and remained still 1.1 times higher in a 7 tesla field applied normally to the tape. The ratio of J/sub c/(B/spl par/(a,b)) to J/sub c/(B/spl perp/(a,b)) starting from 1 for zero applied field was observed to reach 2 in a field. Finally, the pinning potential of the materials were determined accounting silver backing correction (dependence resistivity as a function of magnetic field is incidentally presented too).