M. Ricci

Test of the ITER central solenoid model coil and CS insert

The Central Solenoid Model Coil (CSMC) was designed and built from 1993 to 1999 by an ITER collaboration between the U.S. and Japan, with contributions from the European Union and the Russian Federation. The main goal of the project was to establish the superconducting magnet technology necessary for a large-scale fusion experimental reactor. Three heavily instrumented insert coils were built to cover a wide operational space for testing. The CS Insert, built by Japan, was tested in April-August of 2000. The TF Insert, built by Russian Federation, will be tested in the fall of 2001. The NbAl Insert, built by Japan, will be tested in 2002. The testing takes place in the CSMC Test Facility at the Japan Atomic Energy Research Institute, Naka, Japan. The CSMC was charged successfully without training to its design current of 46 kA to produce 13 T in the magnet bore. The stored energy at 46 kA was 640 MJ. This paper presents the main results of the CSMC and the CS Insert testing-magnet critical parameters, ac losses, joint performance, quench characteristics and some results of the post-test analysis.

ITER CS model coil and CS insert test results

The inner and outer modules of the central solenoid model coil (CSMC) were built by US and Japanese home teams in collaboration with European and Russian teams to demonstrate the feasibility of a superconducting central solenoid for ITER and other large tokamak reactors. The CSMC mass is about 120 t; OD is about 3.6 m and the stored energy is 640 MJ at 36 kA and peak field of 13 T. Testing of the CSMC and the CS insert took place at Japan Atomic Energy Research Institute (JAERI) from mid March until mid August 2000. This paper presents the main results of the tests performed,.

First test results for the ITER central solenoid model coil

Abstract The largest pulsed superconducting coils ever built, the Central Solenoid (CS) Model Coil and Central Solenoid Insert Coil were successfully developed and tested by international collaboration under the R&D activity of the International Thermonuclear Experimental Reactor (ITER), demonstrating and validating the engineering design criteria of the ITER Central Solenoid coil. The typical achievement is to charge the coil up to the operation current of 46 kA, and the maximum magnetic field to 13 T with a swift rump rate of 0.6 T/s without quench. The typical stored energy of the coil reached during the tests was 640 MJ that is 21 times larger than any other superconducting pulsed coils ever built. The test have shown that the high current cable in conduit conductor technology is indeed applicable to the ITER coils and could accomplish all the requirements of current sharing temperature, AC losses, ramp rate limitation, quench behavior and 10 000-cycle operation.

Test of the NbAl insert and ITER central solenoid model coil

The Central Solenoid Model Coil (CSMC) was designed and built by an ITER collaboration in 1993-2001. Three heavily instrumented Inserts have been also built for testing in the background field of the CSMC. The Nb/sub 3/Al Insert was designed and built by Japan to explore the feasibility of an alternative to Nb/sub 3/Sn superconductor for fusion magnets. The Nb/sub 3/Al Insert coil was tested in the CSMC Test Facility at the Japan Atomic Energy Research Institute, Naka, Japan in March-May 2002. It was the third Insert tested in this facility under this program. The Nb/sub 3/Al Insert coil was charged successfully without training in the background field of the CSMC to the design current of 46 kA at 13 T peak field and later was successfully charged up to 60 kA in 12.5 T field. This paper presents the test results overview.

Preparation of the ITER poloidal field conductor insert (PFCI) test

The Poloidal Field Conductor Insert (PFCI) of the International Thermonuclear Experimental Reactor (ITER) has been designed in the EU and is being manufactured at Tesla Engineering, UK, in the frame of a Task Agreement with the ITER International Team. Completion of the PFCI is expected at the beginning of 2005. Then, the coil shall be shipped to JAERI Naka, Japan, and inserted into the bore of the ITER Central Solenoid Model Coil, where it should be tested in 2005 to 2006. The PFCI consists of a NbTi dual-channel conductor, almost identical to the ITER PF1 and PF6 design, /spl sim/45 m long, with a 50 mm thick square stainless steel jacket, wound in a single-layer solenoid. It should carry up to 50 kA in a field of /spl sim/6 T, and it will be cooled by supercritical He at /spl sim/4.5 K and /spl sim/0.6 MPa. An intermediate joint, representative of the ITER PF joints and located at relatively high field, will be an important new item in the test configuration with respect to the previous ITER Insert Coils. The PFCI will be fully instrumented with inductive and resistive heaters, as well as with voltage taps, Hall probes, pick-up coils, temperature sensors, pressure gauges, strain and displacement sensors. The test program will be aimed at DC and pulsed performance assessment of conductor and intermediate joint, AC loss measurement, stability and quench propagation, thermal-hydraulic characterization. Here we give an overview of the preparatory work toward the test, including a review of the coil manufacturing and of the available instrumentation, a discussion of the most likely test program items, and a presentation of the supporting modeling and characterization work performed so far.

Development of high-current high-field conductors in Europe for fusion application

In the framework of the preparation for the realization of the international thermonuclear experimental reactor (ITER), the construction and test of relevant models of seven different parts of the reactor was decided. Two of them are related to the superconducting coils: the toroidal field model coil (TFMC) and the central solenoid model coil (CSMC). For these superconducting coils, due to the expected high values of the current (≥60 kA) and voltage (≥5 kV with respect to the ground) the adopted technology was that of cable in conduit conductor (CICC). Until recently, little experience of this technology existed. Therefore, an extensive research and development programme has been carried out, in the last 10 years, by the ITER partners and particularly in Europe, to design, industrialize and test these large conductors and their joints. The EURATOM associations CEA and ENEA played a leading part in this phase. The CICC concept is described and the results of the developments are presented. About 7 km of conductors were manufactured in the industry and for that more than 10 tonnes of Nb3Sn strands were produced in Europe. In this large programme, Europe is particularly in charge of the TFMC, which will be tested this summer at Forschung Zentrum Karlsruhe (Germany). In the framework of this programme, three full size conductors and joint samples were tested at the European Sultan test facility (Centre de Recherches de Physique des Plasmas, Villigen, Switzerland), to validate the technological choices and check that the ITER specifications were met. The results of these tests are presented in detail. Starting from the strand critical properties, the conductors made of about 1000 strands did reach their expected performance. The joints of these large conductors are very special and delicate components. Their behaviour was quite successful and the joint resistance of these samples (of the order of 1 nΩ) was well within the specifications.

Completion of the ITER Toroidal Field Model Coil

In the scope of the ITER EDA a Toroidal Field Model Coil (TFMC) has been manufactured accompanied by a thorough Quality Assurance (QA) test program. This large superconducting coil has been conceptually designed by the ITER European Home Team (EUHT) and manufactured by European industry. The coil is being completed and will be tested at the Forschungszentrum Karlsruhe in spring 2001. The race track shaped winding is made of a cable-in-conduit conductor in a circular 316LN stainless steel jacket. From this conductor five double pancake (DP) modules were fabricated. Results of conductor and DP manufacture were already presented at previous conferences and are therefore only summarized here. The paper concentrates on the subsequent manufacturing steps, namely the stacking of the DP modules, the insulation and impregnation of the winding pack, the outer joint manufacture by electron beam welding, the assembly of the winding pack with the stainless steel case, the mounting of the helium pipes, the sensors and the busbars. To assemble the coil into the TOSKA facility and to fit it to the EU-LCT coil a heavy Inter-Coil Structure (ICS) has been built, in which the TFMC will rest on four wedges.

Assembly in the test facility, acceptance and first test results of the ITER TF model coil

As a joint European effort an ITER Toroidal Field Model Coil (TFMC) was manufactured in industry and has been assembled in the TOSKA test facility of the Forschungszentrum Karlsruhe. After cool down and acceptance tests of the racetrack shaped coil made of a Nb/sub 3/Sn cable in conduit conductor the first test campaign started in July 2001 reaching the design current of 80 kA within one week. This paper describes the assembly in the test facility, summarizes the acceptance tests before and after cool down, and reports on the first test results.

Implications of NbTi Short-Sample Test Results and Analysis for the ITER Poloidal Field Conductor Insert (PFCI)

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

Impact of void fraction on mechanical properties and evolution of coupling loss in ITER Nb/sub 3/Sn conductors under cyclic loading

The combination of current up to 50 kA and magnetic field of 13 T in the Cable-In-Conduit Conductors (CICC) for the coils in the International Thermonuclear Experimental Reactor (ITER), cause huge local transverse forces. This results in changes in the transport properties, friction and anomalous contact resistance versus force behavior. The latest design optimizations tend to go toward a lower void fraction (VF). This has an impact on the evolution of the coupling loss and on the possible degree of strand bending and deformation. Toroidal Field Model Coil (TFMC) type of conductors with VFs of 26%, 30% and 36% respectively, are tested in the Twente Cable Press, by which a variable (cyclic) transverse force of 650 kN/m is transferred directly to a cable section of 400 mm length at 4.2 K. The AC loss of the conductor, the inter-strand and strand-bundle resistance (R/sub c/) in the cable and the associated bundle deformation are examined during mechanical cycling. The test results are discussed in view of the previous results on Nb/sub 3/Sn ITER CICCs.