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The ITER Magnet System contains 18 Toroidal Field Coils (TFC). These are large D-shaped coils of about 300 t, 17.5-m height and 9-m width. They consist of a Winding Pack (WP) enclosed in a rigid structural steel case, the Toroidal Field Coil Case (TFCC). The WP is a bonded structure of 7 Double Pancakes (DP), each made up of a radial plate (RP) housing the reacted Nb3Sn cable-in-conduit superconductor (CICC), which operate at 4.5 K in supercritical helium. The conductor carries a current of 68 kA in operation to produce a nominal peak field of 11.8 T. The total stored magnetic energy in the 18 TFCs is 41 GJ. While the Japanese and European Domestic Agencies that are in charge of the procurement of the TFCs are progressing with the manufacturing design and the fabrication trials prior to launch the production of the real coils, the ITER Organization (IO) is completing the development and qualification of the most critical items, e.g. cyanate ester and resin blends for the conductor and WP insulation system, the terminal region, the helium inlet, a charged resin system for the filling of the gap between the WP and the TFCC and the general tolerancing especially at the interfaces between the neighboring systems. This paper presents the final design of the TFCs and the results of the developments carried out in the aforementioned areas in the last 2 years. [ABSTRACT FROM PUBLISHER]

The ITER superconducting magnet system (Toroidal Field coils (TF), Central Solenoid (CS), Poloidal Field coils (PF), Correction Coils (CC) and Feeders) represents a total weight of approximately 10 000 tons. It is designed to withstand gravitational and seismic forces, stresses induced by thermal contractions during cool-down from 300 K to 4.5 K, and large Lorentz forces in the superconducting coils. Although not part of the Safety Important Class (SIC) components, the sensors (stress, displacement, thermometer) used to monitor the thermo-mechanical behavior of the structures are key diagnostic means to assess the design, support operation and survey possible fatigue effects over the 20 years' lifetime of the Tokamak. The sensors and their wiring will be submitted to unique and severe environmental operating conditions; they will have to operate in the cryostat's high vacuum (<10^-4\ Pa total gas pressure) at magnetic inductions of several Tesla and at low temperature (4.5 K) in the presence of a neutron fluence on the order of 10^22\ m^-2—which implies a gamma dose higher than 10 MGy—for a period of 20 years. In addition, the fast and slow cycling of very large currents in the superconducting magnets and plasma will generate large eddy currents and, consequently, heat loads and electromotive forces (voltages) in the various parts of the structures, as well as a large electromagnetic noise. This paper presents the design philosophy and the chosen sensor technologies, some of which require further development in collaboration with the industry so that they can meet the objectives and the severe ITER operating conditions. In particular, only 20% of the near 1 000 measuring points for the thermo-mechanical data of the ITER magnet structures will rely on “classical” copper-wire technologies whereas 80% will rely on specifically developed optical-fiber-based sensors. [ABSTRACT FROM PUBLISHER]

The R&D of the manufacture related technology for ITER magnet supports is one of the tasks for construction. In this paper, we report the recent progress on alternative design for the Toroidal Field Support (TFS) manufacture without welding and its related structural analysis; the engineering test of the prototype TFS mock-up under various load combinations; the arc-brazing of cooling pipe to supports technology and its result; the ion implantation for improving the wear resistance of strut dowel in the Poloidal Field (PF) coils PF3-4 support system and the plasma spray insulation coating for correction coil support (CCS). [ABSTRACT FROM PUBLISHER]

The ITER TF Coils will consist of two main components; the WP which is formed by the assembly of seven double pancakes, superconducting windings inserted into stainless steel radial plates and the stainless steel structural casing which forms the mechanical interface between TF coils and the remainder of the ITER machine. The final step in assembly of the TF Coils will be the insertion of the WP into the structural casing. The insertion procedure must achieve two critical objectives; accurate geometric location, +/-1 mm, of the WP current center line with respect to the casing reference faces and the full mechanical location of the WP within the casing to facilitate the uniform transfer of the electromagnetic forces to the casing and the ITER TF keystone structure. [ABSTRACT FROM AUTHOR]

The Correction Coils (CC) of the ITER Tokamak are developed to reduce the range of magnetic error fields created by imperfections in the location and geometry of the other coils used to confine, heat, and shape the plasma. The proposed system consists of three sets of 6 coils each, located at the top (TCC), side (SCC) and bottom (BCC) of the Tokamak device and using a NbTi cable-in-conduit superconducting conductor (CICC). Within each set, the coils are connected in pairs to produce a toroidal field to reduce the most troublesome, lower order, poloidal mode number fields (m = 1,2,3) in order to operate below the locked mode threshold. The conductor is designed to operate up to 6 T. The winding uses pancakes of one-in-hand conductor (quadpancakes for SCC, octopancakes for TCC and BCC), thus avoiding internal joints. The winding-pack is enclosed inside a 20 mm thick stainless steel casing. The coils are supported by rigid connections to the Toroidal Field (TF) coils. The structural design of the CC is mainly driven by the allowable fatigue stress levels in the conductor jacket, in the case material and in the glass-polyimide electrical insulation system. The boundary conditions on the CC are imposed by the TF coils deformation and the electromagnetic interactions with the PF coils system. The thermo-hydraulic and electrical performance of the CICC is also addressed. [ABSTRACT FROM AUTHOR]

The magnet system for ITER comprises 18 Toroidal Field (TF) Coils using Nb3Sn cable-in-conduit superconductor, which operate at 4.5 K in supercritical helium. The procurement of the TF Coils and Structures is amongst the first which have been launched following the creation of the ITER Organization (IO). It is organized in 4 phases. A Procurement Design Readiness Review held in April 2008 confirmed the readiness of the design to proceed with Phases I and II. Procurement Arrangements (PA) were signed with the European and Japanese Domestic Agencies (DA) respectively in June and November 2008. After a brief description of the TF Coils and Structures, the paper gives an overview of the PA showing the milestones towards series production. The procurement strategy of both DA involved is described, in particular the first step which covers pre-production activities: qualification of raw materials, manufacturing trials, mock-ups and full-scale prototype radial plates, impregnation tests and, possibly, winding trials. The work carried out by IO is also presented: optimization of the cover plate welding to satisfy the allowable stress criteria while minimizing the associated distortions, qualification of blends of cyanate ester with epoxy resin for the impregnation of the winding packs and design of the coil terminal region including integration of the needed instrumentation. [ABSTRACT FROM AUTHOR]

The toroidal magnetic field of ITER is provided by 18 Nb3 Sn superconducting coils that provide 5.3 Tin the Tokamak magnetic centre thanks to a nominal current of 68 kA. Two major procurement packages will be integrated to accomplish the final assembly of the coils: 1) the winding pack which houses the double pancakes in 7 stacked radial plates (RP) and 2) the TF coil case which houses the winding pack (WP) and is the main structural component of the ITER machine. 19 TF coil cases (18+1 spare) will be entirely procured by Japan, whereas the WP and the TF coil assembly will be shared between Japan (9) and Europe (10). The insertion process of the WP inside the coil case, VPI and final closure welding is presented with an emphasis on the R&D still remaining. An appropriate metrology strategy and correct benchmarking of the WP current center line (CCL) in the coil case external walls is essential to allow the correction of the error fields during operation. The TF coils will be assembled and pre-aligned in pairs together with their corresponding VV sector and craned to the Tokamak hall hanging from 2 independent hooks. The integration of the IF coils in the Tokamak primary datum system will have to bc accomplished within the maximum tolerances defined by the error field analysis. As-built 3D data collected during manufacture will be used to ensure the correct positioning of the CCL against the Tokamak datum system and ease the alignment process. Shimming will be used in the gravity support for vertical alignment and in the upper and lower OIS for toroidal alignment. A subsequent survey of the `as-installed' TF coils will determine the final Tokamak Datum System. [ABSTRACT FROM AUTHOR]

The current design of the ITER Toroidal Field coils and structures, the main critical design and manufacturing issues, and the status of the procurement arrangements for these components, which will be released to the ITER parties in early 2008 to start the manufacturing contracts, are described. Some qualification and R&D work still required in preparation for the manufacture are also mentioned. [ABSTRACT FROM AUTHOR]

Procurement of the ITER magnets is due to start at the end of 2007/early 2008, with the launch of the longest lead time items, the Nb3 Sn conductor and the TF coil windings. The base design for procurement was established in 2001, and the build up of the Cadarache ITER team has been accompanied by a review of the most critical, or controversial, features of the 2001 design. At the same time, an urgent R&D program has been launched to complete the necessary verification of the design solutions that are proposed. In this paper an overview will be presented of the main design features and drivers, and some of the recent issues and R&D results will be summarized. [ABSTRACT FROM AUTHOR]