B. Turck - IEEE Xplore Author Profile

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While the ITER magnet system assembly is progressing, models are being developed to predict the performances of the coils in preparation of the ITER magnet commissioning and operation. In particular, the AC losses generated in the conductors during a plasma scenario need to be estimated in order to predict the magnet thermo-hydraulic performances. The largest AC losses during plasma operation are ...Show More
AC losses induced by magnetic field variations dissipate power in the conductors of coils during the tokamak operation. They can be critical for being a possible source of resistive transitions and leading to a possible quench in the magnet. This paper aims at presenting the results of the influence of the applied field direction on these losses. The measurements are carried out at the JOSEFA faci...Show More
In this paper, we aim at describing the hysteretic losses in superconducting conductors in the specific case of multiple field reversals in partial penetration, which produces a complex field profile in the superconductor, and which happens quite extensively in complex field scenarios like those of fusion magnets. The paper will introduce the usual analytical formulas used for computing the hyster...Show More
While the ITER magnet system assembly is progressing, models are being developed to predict the performances of the coils in support of the preparation of commissioning and operation. In particular, the AC losses generated in the coils during a plasma scenario need to be estimated as input to thermo-hydraulic performance simulations. The largest AC losses during plasma operation are expected in th...Show More
While the ITER Magnet system is being assembled at Cadarache (France), models are being developed on the basis of the conductors test results. The purpose is to prepare the performances extrapolation to magnet commissioning and operation. In particular, the AC losses generated in the conductors during a plasma scenario should be estimated in order to predict potential operating margins reductions ...Show More
AC loss is a major heat load in the pulsed, superconducting ITER coils, and thus a design driver for the cryo-system and superconductor. Given the importance of AC loss, extensive AC loss characterization of the components of the ITER coils, from the superconducting strands, cables, long “coil-like” conductors (so called insert-coils) to the completed coils, were conducted over the past years. Rec...Show More
Cable-in-Conduit Conductors (CICC) are made of several hundreds of superconducting and copper strands twisted together and gathered into multiple stages. To ensure safe and reliable operation of tokamaks, it is essential to take into account AC losses occurring in such conductors. Recently developed at CEA, the fully analytical model named COLISEUM (COupling Losses analytIcal Stages cablEs Unified...Show More
During the years of ITER conductors qualification and production, samples from all domestic agencies were tested. Some of these tests were focused on characterizing the AC losses properties of the ITER conductors. The data produced originate from various facilities (PSI, University of Twente, CERN), using different experimental and data reduction protocols, for a large number of samples. The resul...Show More
Predicting analytically the coupling losses generated in a cable for fusion magnets is still a significant challenge. Difficulties are related to the complex geometry of the system: several multi-strand stages embedded in one another with different twist pitches length, difficulty to model multiplets of strands, including compaction to the final shape. A two-stage analytical geometry based model (...Show More
AC losses deposited in the magnets during JT-60SA commissioning and operation will both affect the local stability of the conductor and act as a load on the cryogenic system. Our objective is thus to establish a detailed modeling of AC losses generated in the magnets by different current scenarios. Since the TF coils have been tested in the Cold Test Facility (CTF) and will be the first ones to be...Show More
Modelling by analytical approach the coupling losses of CICCs used in tokamaks remains a challenge to be reliable. This is usually done using either CPU consuming numerical approaches or heuristic models such as MPAS now used for ITER. Experimental measurements of AC losses are performed at CEA using magnetization method on several type of JT-60SA TF samples with various void fractions (25%-36%). ...Show More
In spite of their complex geometry, cable in conduit conductors (CICCs) have to be modelled with a rather simple description for coupling losses when operating in transient regime. Difficulties to predict ac losses in superconducting cable have already been shown in previous models such as the new analytical one developed at CEA named COLISEUM (after Coupling Losses analytical Staged cables Unifie...Show More
Coupling losses induced in cable-in-conduit conductors (CICC) when subject to a time-varying magnetic field are a major issue commonly encountered in large fusion tokamaks (e.g., JT-60SA, ITER, DEMO). The knowledge of these losses is crucial to determine the stability of CICC but is yet difficult to achieve analytically (thus in a short computation time) given the specific and complex architecture...Show More
The superconducting coils of the ITER magnet system have hundreds of electrical lap joints interconnecting superconducting cables. The joints operate in a magnetic field of up to 4 T, field derivatives of 0.5 T/s, and currents up to 70 kA. The acceptance tests for the toroidal field (TF), poloidal field (PF), and correction coil (CC) coils will be performed at 77 K, before they are assembled in th...Show More
Cable-in-conduit conductors (CICCs) are composed of a large number of strands (superconducting composites and copper strands) twisted together in several stages with different twist pitches. They are widely used in large fusion tokamaks such as JT-60SA or ITER. However, because of their complex transposed geometry at a strand scale, the knowledge of ac coupling losses in these conductors is limite...Show More
Previous analytical models of ac coupling losses in multifilamentary composites under a time-varying external magnetic field were developed for specific strand geometries. Therefore, no global expression of coupling losses was established for any circular geometry. The purpose of this paper is, thus, to present the general analytical strategy and the assumptions of the model developed at CEA. Furt...Show More
One of the critical components of the ITER poloidal field (PF) coils is the electrical joint connecting two conductor lengths. The lap “shaking hands” joints will operate under variable field, causing parasitic-induced currents in superconducting strands and temperature rise of the strands. Previously, some design changes for decreasing the induced currents in the joints were proposed and assessed...Show More
An ITER Poloidal Field coil winding consists of stacked double pancakes wound with NbTi cable-in-conduit conductors. One of the critical components of the coil is the electrical joint connecting either two conductor lengths within a double pancake or two double pancakes. All joints utilize the twin-box “shaking hands” concept. It has previously been found with the JackPot-AC numerical model that i...Show More
During a plasma disruption a complex map of magnetic field variation is generated along the JT-60SA TF conductor. The current variations associated with a symmetric plasma disruption are modeled in JT-60SA, on the basis of a circuit approach. The main components of the circuit model are: the poloidal field coils, the plasma represented by circular filaments, the vacuum vessel, and the stabilizing ...Show More
Under fast magnetic field variations, ac losses are deposited in a Cable in Conduit Conductor (CICC). The corresponding power losses are transferred to helium thanks to the high wetted perimeter of the conductor. The critical energy of the CICC can be expected to be proportional to the high volumetric heat capacity of helium and to the temperature margin. To confirm the expectations, stability tes...Show More
The upgrade of JT-60U to JT-60 Super Advanced (JT-60SA), a fully superconducting tokamak, will be performed in the framework of the Broader Approach (BA) agreement between Europe (EU) and Japan. In particular, the Toroidal Field (TF) system, which includes 18 coils, is foreseen to be procured by France, Italy and Germany. This work covers activities from design and manufacturing to shipping to Jap...Show More
A study was undertaken to outline a long pulse D-T tokamak dedicated to plasma physics close to reactor conditions but still operating at limited values of fusion power (P/sub fusion/=200 MV) and amplification factor. Such a machine would not reach ignition and would not envisage a programme of irradiation of materials with high fluence. This makes it possible to slacken the technical constraints,...Show More
The operational performance, during the last 10 years, of the toroidal field (TF) system of the Tokamak TORE SUPRA based at CEA Cadarache, has demonstrated that superconductivity associated to superfluid helium is a reliable and realistic option for fusion by magnetic confinement. This solution is now widely used in cryoelectricity. With superfluid helium associated to cable in conduit superconduc...Show More
Tore Supra is the largest Tokamak with superconducting coils. This unique feature enables a large part of the physics programme to be dedicated to long pulse operation (30-60 s). After a brief description of some peculiar aspects of the Tore Supra magnets, the paper reports about the 6 year operating experience. Particular emphasis is put on the mechanical behaviour of the coils under repetitive l...Show More
The aims of the toroidal field (TF) model coil are to test the manufacturing feasibility of the ITER TF magnet concepts, to assess the reliability of the fully integrated system by dedicated testing and to qualify the quality assurance and the testing methods. The 3.8 m long racetrack shaped TFMC will be tested in the TOSKA facility at Karlsruhe in a configuration using the Euratom LCT Coil to pro...Show More