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Four samples of full size ITER toroidal field (TF) conductor are manufactured according to the conductor layout defined by ITER. The manufacturing procedures and the dc test under relevant load conditions are described.

Two European ITER toroidal field (TF) prototype samples are prepared, assembled and tested in SULTAN. The ITER specifications are fulfilled by both samples, with outstanding results for the conductor with longer twist pitches.

High-energy physics (HEP) type [Nb.sub.3]Sn strands with a [J.sub.c] ~ 2400 A/[mm.sup.2] are applied to a steel Cable-in-Conduit Conductors (CICC). The high-field (HF) conductor qualification process, the design modifications and the analysis of the test results are discussed.

An alternative solution is described by using a relatively thin walled rectangular conductor without an additional reinforcing structure. The conductor and the layout of the winding, the magnetic, thermo-hydraulic and mechanical behavior of the ITER toroidal field (TF) coils are analyzed.

A 12.5 T superconducting dipole magnet (European DIPOle, EDIPO) is designed by EFDA, which is procured within the framework of the European Fusion Programme in order to be installed in CRPP-PSI. The magnet parameters are described together with the key supporting electromagnetic, mechanical and thermal analyses.

The Poloidal Field Coil 6 (PF6) coil design based on [Nb.sub.3]Sn superconductor, which has delivered the required temperature margin as well as the higher performance capability, is examined. The design analysis has discussed the performance parameters of the coil including the hot spot temperature and quench propagation.

The test results of the new generation of ITER TF conductor samples in SULTAN are discussed. The homogenization of performance toward the upper range has provided an effective margin for the operation of the ITER coil system.

A new joint design is developed and patented by ENEA in the framework of the EFDA dipole (EDIPO) activities. The analysis has shown a resistance < 0.5 n[omega], while the first trial of adapting it to the EDIPO realization needs have given a value 10 times higher.

Two conductor short samples were tested for examining the use of high current [Nb.sub.3]Sn strands in International Thermonuclear Experimental Reactor (ITER) cable-in-conduit conductors (CICC). Findings revealed the strong degradation of the CICC performance in comparison to the strand for all conductors.

The predictive analysis of the International Thermonuclear Experimental Reactor (ITER) Poloidal Field Conductor Insert (PFCI) test program is presented. PFCI is the first insert coil based on NbTi and is aimed at bridging the extrapolation gap between its full-size short sample and the ITER Poloidal Field (PF) coils.

The study explains various pure bending strain experiments conducted on several jacketed [Nb.sub.3]Sn strands for International Thermonuclear Experimental Reactor (ITER).

The tests of the Toroidal Field Model Coil (TFMC) are completed in the TOSKA facility of Forschungszentrun Karlsruhe. The TFMC isolated strand is characterized at different applied uniaxial strain, and preliminary results indicate a stronger reduction of carrying capacity compared to the extrapolation from summers scaling used in the analysis.

Toroidal Field Model Coil (TFMC) design and fabrication alternatives are discussed. Test results and experience gained during the TFMC's assembly are presented.

Assembly and testing of the International Thermonuclear Experimental Reactor's (ITER) Toroidal Field Model Coil (TFMC) is described and discussed. This work was accomplished at the TOSKA facility of the Forschungszentrum Karlsruhe, Karlsruhe, Germany.

The ITER toroidal field model coil is considered in terms of its manufacture, assembly and QA methods.

The results of tests carried out on three Nb3Sn cable-in-conduit conductors are discussed. The tests, which investigated the viability of the superconducting elements for the Next European Torus program, were conducted under conditions exceeding the conductor's rated capacity. The results provide a measure of the temperature margin during dc operation and the pressure drop.

The EU development effort for International Thermonuclear Experimental Toroidal Field (TF) and Central Solenoid (CS) Model Coils (MC) are reported. The EU's TFMC effort involves 4t of internal tin Nb3Sn cabling and strand and jacketing of 1 km TF conductor. For CSMC, 1200m of full size cable, 6.5t of bronze Nb3Sn strand and 5787m conductor jacketing are being produced. Developments and limitations of manufacturing processes are also discussed.

The design and fabrication of two types of Nb3Sn strands for the International Thermonuclear Experimental Reactor test coils are discussed. The first, which has specifications for high current densities and fabrication via the internal tin process, is currently under development at Italy's EM-LMI. The second, which has specifications for low hysteresis losses and fabrication via the bronze process, has already been developed and demonstrated by Germany's Vacuumschmelze.

Abstract-Recent studies have shown that the presently considered conductor for the Poloidal Field Coil 6 (PF6) of the ITER machine is being designed at the limit of what the considered NbTi superconductor can deliver. Furthermore tests have shown that the performance of conductor prototypes remained under the specified 1.5 K temperature margin. As a result of these issues, ITER is considering a PF6 coil design using Nb3 Sn superconductor. We have investigated a PF6 coil design based on Nb3 Sn superconductor, which at the same time delivers the required temperature margin as well as the higher performance capability at a similar cost as the reference NbTi design. In addition the design analysis presented here discusses performance parameters such as hot spot temperature and quench propagation. Finally we also present possible coil design and manufacturing procedures. [ABSTRACT FROM AUTHOR]

The effect of transverse loads on Nb3Sn strands has been pointed as a possible cause of the difference observed when scaling transport properties of single strands to those of cable-inconduit conductors. Single multifilamentary strands inside cables are in fact subject to bending strain due to the electromagnetic forces at operating conditions and to the geometrical layout. Here the influence of pure bending strain, applied in combination with a longitudinal strain, on the critical current of Nb3Sn advanced strands for ITER has been studied. The tested samples are single strands inserted inside a thin stainless steel jacket and wound on stainless steel barrels. After the heat treatment, a pure bending strain has been applied transferring the wires on different diameter mandrels, using ad-hoc developed and qualified techniques. Transport critical current has been measured on the single strands before and after the steel jacketing, as well as after the additional application of two different values of maximum bending strain: 0.5% and 0.25%. This was the best choice in order to verify experimentally whether the so-called long twist pitch condition can be applied for the selected strands. The distribution of the bending strain over the strand cross-section has been calculated with finite element numerical codes, and the expected critical current degradation in the limiting cases of short and long twist pitch has been computed and compared with experimental data. [ABSTRACT FROM AUTHOR]

Two short length samples have been prepared and tested in SULTAN to benchmark the performance of high current density, advanced Nb3Sn strands in the large cable-in-conduit conductors (CICC) for ITER. The cable pattern and jacket layout were identical to the Toroidal Field Model Coil Conductor (TFMC), tested in 1999. The four conductor sections used strands from OST, EAS, OKSC and OCSI respectively. The Cu:non-Cu ratio was 1 for three of the new strands, compared to 1.5 in the TFMC strand. The conductors with OST and OKSC strands had one Cu wire for two Nb3Sn strands, as in TFMC. In the EAS and OCSI conductors, all the 1080 strands in the cable were Nb3Sn. A dc test under relevant load conditions and a thermal-hydraulic campaign was carried out in SULTAN. The CICC performance was strongly degraded compared to the strand for all the four conductors. The current sharing temperature at the ITER TF operating conditions (jop = 286 A/mm², B = 11.15 T) was lower than requested by ITER. [ABSTRACT FROM AUTHOR]

Within the framework of ITER-related projects, new tasks have been recently launched by EFDA CSU Garching (European Fusion Development Agreement Close Support Unit Garching), for the definition and production on industrial scale of advanced Nb3Sn strands, to be used in the manufacturing of the ITER high field CS and TF magnets. We performed an extended characterization of the advanced Nb3Sn strands coming from different European companies, in terms of strand layout (diameter, thickness of Cr coating, Cu:non-Cu ratio), critical transport current, RRR, and hysteresis losses. The results of the measurement campaign show that the upgraded strands meet the latest ITER requirements, with an overall critical transport current of at least 200 A (at 12 T, 4.2 K), equivalent to a non-Cu Jc of about 800 A/mm², a Cu:non-Cu ratio of about 1, a strand diameter of 0.81 mm, and with non-Cu hysteresis losses limited to less than 1000 kJ/m³ on a ±3 T field cycle at 4.2 K. [ABSTRACT FROM AUTHOR]

In the scope of the design activities for a 12.5 T dipole magnet, a short length of cable-in-conduit conductor (CICC) with steel jacket was prepared in spring 2005 as a pre-prototype of the high field dipole conductor. The small, rectangular conductor uses for the first time ‘advanced’ Nb3Sn strands, with Jc = 1100 A/mm² at 12 T, 4.2 K, also planned in the qualification samples for the ITER conductors. At CRPP, a hairpin sample for SULTAN has been prepared from the short conductor length, heat treated and instrumented. The test program included pressure drop, AC losses and full DC characterization before and after cyclic loading. At large, the test results indicate that the high performance of the advanced strands is preserved in the small size, steel jacketed CICC. [ABSTRACT FROM AUTHOR]

As the test of the PFCI is foreseen in 2006 at JAERI Naka, Japan, it is essential to consider in detail the lessons learned from the short NbTi sample tests, as well as the issues left open after them, in order to develop a suitable test program of the PFCI aimed at bridging the extrapolation gap between measured strand and future PF coil performance. Here we consider in particular the following issues: 1) the actual possibility to quench the PFCI conductor in the Tcs tests before quenching the intermediate joint, 2) the question of the so-called sudden or premature quench, based on SULTAN sample results, applying a recently developed multi-solid and multi-channel extension of the Mithrandir code to a short sample analysis; 3) the feasibility of the AC losses calorimetry in the PFCI. [ABSTRACT FROM AUTHOR]

One of the most important characteristics of Nb3 Sn strands is the strain dependence of the critical current density which has to be taken into account for every conductor design, especially for cable-in-conduit conductors (CICC) due to the additional influence of the jacket material. Therefore, a task has been launched in the framework of the European Fusion Technology Program to determine the residual thermal strain of single strands and different multi-stage conductors on absolute scale which is essential for the final optimization of the ITER TF conductor. For this purpose, an existing test rig for critical current measurements on single strands and multi-stage CICC as a function of strain and field, the FBI facility at the Forschungszentrum Karlsruhe, has been recently modified and modernized to improve the overall accuracy and resolution of the system. After a description of the facility, its capabilities and the recently performed upgrades, this paper explains the scheduled test program and the strategy to assess the impact of the cable pattern and size on the residual thermal strain. Results on Nb3 Sn sfrands jacketed in stainless steel are presented as well. [ABSTRACT FROM AUTHOR]

The Bus Bar III (BBIII), fabricated within the Toroidal Field Model Coil Task of the International Thermonuclear Experimental Reactor (ITER), was tested at the Forschungszentrum Karlsruhe, Germany, in the spring of 2004. The BBIII consists of an approximately 7 m long NbTi dual-channel conductor with a thick square stainless steel jacket, cooled by forced flow supercritical He. It was energized with currents up to 80 kA and operates in its self magnetic field (up to ∼0.8 T). The BBIII was instrumented with Hall-probe heads and arrays, voltage rings and longitudinal voltage taps for electro-magnetic measurements, in order to get experimental data to be used for the validation of a recently developed hybrid thermal-hydraulic electro-magnetic code (THELMA), as well as for the assessment of the possibility of performing a reliable reconstruction of the current distribution in the conductor cross section under controlled conditions. In the tests, current ramps at different rates were applied to characterize the conductor time constants, while two different resistive heaters (one upstream of the BBIII inlet, another one directly on the BBIII jacket) were separately operated in order to approach current sharing in the conductor and to observe the related current re-distribution. In this paper, a summary of the collected experimental results is presented, with particular emphasis on those aspects more relevant for the forthcoming THELMA analysis. [ABSTRACT FROM AUTHOR]