The mission of WEST (tungsten-W Environment in Steady-state Tokamak) is to explore long pulse operation in a full tungsten (W) environment for preparing next-step fusion devices (ITER and DEMO) with a focus on testing the ITER actively cooled W divertor in tokamak conditions. Following the successful completion of phase 1 (2016-2021), phase 2 started in December 2022 with the lower divertor made entirely of actively cooled ITER-grade tungsten mono-blocks. A boronization prior the first plasma attempt allowed for a smooth startup with the new divertor. Despite the reduced operating window due to tungsten, rapid progress has been made in long pulse operation, resulting in discharges with a pulse length of 100 s and an injected energy of around 300 MJ per discharge. Plasma startup studies were carried out with equatorial boron nitride limiters to compare them with tungsten limiters, while Ion Cyclotron Resonance Heating assisted startup was attempted. High fluence operation in attached regime, which was the main thrust of the first campaigns, already showed the progressive build up of deposits and appearance of dust, impacting the plasma operation as the plasma fluence increased. In total, the cumulated injected energy during the first campaigns reached 43 GJ and the cumulated plasma time exceeded 5 h. Demonstration of controlled X-Point Radiator regime is also reported, opening a promising route for investigating plasma exhaust and plasma-wall interaction issues in more detached regime. This paper summarises the lessons learned from the manufacturing and the first operation of the ITER-grade divertor, describing the progress achieved in optimising operation in a full W environment with a focus on long pulse operation and plasma wall interaction.

WEST is an MA class superconducting, actively cooled, full tungsten (W) tokamak, designed to operate in long pulses up to 1000 s. In support of ITER operation and DEMO conceptual activities, key missions of WEST are: (i) qualification of high heat flux plasma-facing components in integrating both technological and physics aspects in relevant heat and particle exhaust conditions, particularly for the tungsten monoblocks foreseen in ITER divertor; (ii) integrated steady-state operation at high confinement, with a focus on power exhaust issues. During the phase 1 of operation (2017-2020), a set of actively cooled ITER-grade plasma facing unit prototypes was integrated into the inertially cooled W coated startup lower divertor. Up to 8.8 MW of RF power has been coupled to the plasma and divertor heat flux of up to 6 MW m(-2) were reached. Long pulse operation was started, using the upper actively cooled divertor, with a discharge of about 1 min achieved. This paper gives an overview of the results achieved in phase 1. Perspectives for phase 2, operating with the full capability of the device with the complete ITER-grade actively cooled lower divertor, are also described.

Currently on fusion devices, diagnostics are mainly aiming at plasma analysis and control. However, operational and programmatic needs have appeared for regular in-vessel components monitoring during plasma campaign. Light robotics systems could meet this requirement and may be a way as well to replace human interventions to fix damaged in vessel components. To minimize the impact on machine operation, the robotic system has to be mini-invasive and compatible with operating conditions (vacuum, temperature.). To fulfill this goal, CEA has developed a multipurpose carrier able to be operated inside WEST vessel between plasma pulses. A prototype of this robot, called Articulated Inspection Arm (AIA), was tested in 2008 in Tore Supra vacuum vessel. A major upgrade was performed in 2014-2015 with the aim of converting this prototype into a reliable tool in support to WEST operation. During the WEST components manufacturing and installation (2014-2016), the robot was integrated and tested in the EAST Tokamak. Since 2017, the AIA has been regularly used during the WEST plasma campaigns. Movies provided by the embedded camera allow to assess the evolution of Plasma Facing Components surface state and the effects of plasma loads, runaways and disruptions. The robot operation was also very helpful to assess the needs for maintenance, to assist mechanical assembly without man entry and to perform diagnostics calibration under relevant conditions.

An articulated inspection arm (AIA) has been developed by CEA for visual inspection between pulses inside the Tore Supra tokamak vacuum vessel without breaking temperature and vacuum conditions. The eight meters length robot is composed of a shuttle and six articulated segments with a video camera at its end. A demonstration prototype has been achieved in 2008 at Tore Supra (Gargiulo, 2007; Houry, 2008; Perrot, 2003).A project to upgrade the AIA into a fully operational robot has been undertaken by IRFM and ASIPP in an Associated Laboratory. It will be in operation first in the EAST machine and afterwards in Tore Supra in its WEST (W/Tungsten Environment in Steady-state Tokamak) configuration where it is of paramount importance to survey possible degradation of W component surface.The control system of the robot has been extensively upgraded. The effort has been focused on three areas: (1) improvement of the arm position accuracy, (2) increase of the operational robustness, (3) use of a powerful graphical user interface including simulation of trajectories and robot deployment capabilities in a 3D viewer environment.The aim of this paper is to detail the architecture of the AIA control system. (C) 2015 Elsevier B.V. All rights reserved.

The configuration of the Tore Supra WEST project leads to control challenges and event handling close to those of ITER from a plasma scenario point of view (X-point configuration, H mode, long duration pulse) and from a machine protection point of view (metallic environment). Based on previous conceptual studies and to meet the WEST requirements, a sub-project will implement a new plasma control system (PCS) and a new pulse schedule editor (PSE). The main idea is to use a segment approach to describe the pulse scheduling with a full integration of event handling both on the PCS and on the PSE. After detailed specification work, it has been shown that the real-time framework called DCS (Discharge Control System) which is currently used on ASDEX upgrade fulfills the requirements and could be integrated into the WEST global control infrastructure. For the PSE, the Xedit tool, developed for the future W7X facility, has been chosen. This contribution will begin by a short explanation of the concepts proposed for the control of the plasma and the handling of events during the plasma discharge. Then it will focus on the new centralized architecture of the new Tore Supra PCS and an operating principle example showing the efficiency of the approach to handle normal and off-normal events. This later point will illustrate the required modifications of DCS and Xedit to fit with the Tore Supra Control infrastructure.

To operate advanced plasma scenario (long pulse with high stored energy) in present and future tokamak devices under safe operation conditions, the control requirements of the plasma control system (PCS) leads to the development of advanced feedback control and real time handling exceptions.To develop these controllers and these exceptions handling strategies, a project aiming at setting up a flight simulator has started at CEA in 2009. Now, the new WEST (W Environment in Steady-state Tokamak) project deals with modifying Tore Supra into an ITER-like divertor tokamak. This upgrade impacts a lot of systems including Tore Supra PCS and is the opportunity to improve the current PCS architecture to implement the previous works and to fulfill the needs of modern tokamak operation.This paper is dealing with the description of the architecture of WEST PCS. Firstly, the requirements will be presented including the needs of new concepts (segments configuration, alternative (or backup) scenario, ...). Then, the conceptual design of the PCS will be described including the main components and their functions.The third part will be dedicated to the proposal RT framework and to the technologies that we have to implement to reach the requirements. (C) 2014 Elsevier B.V. All rights reserved.

In parallel to the direct contribution to the procurement phase of ITER and Broader Approach, CEA has initiated research & development programmes, accompanied by experiments together with a significant modelling effort, aimed at ensuring robust operation, plasma performance, as well as mitigating the risks of the procurement phase. This overview reports the latest progress in both fusion science and technology including many areas, namely the mitigation of superconducting magnet quenches, disruption-generated runaway electrons, edge-localized modes (ELMs), the development of imaging surveillance, and heating and current drive systems for steady-state operation. The WEST (W Environment for Steady-state Tokamaks) project, turning Tore Supra into an actively cooled W-divertor platform open to the ITER partners and industries, is presented.

Coping with unexpected events is an important issue of nuclear fusion experiments. The future machines, characterized by very long plasma discharges and actively cooled metallic plasma-facing components, will require a systematic intervention in real time, in order to maximize the performance and protect the investment. The real-time management of events will require extending the functionalities of the current pulse schedule editors with the possibility of using reference waveforms provided with acceptability margins and setting up advanced mitigation strategies and event countermeasures. With this purpose, a new pulse schedule editor, based on a time-segment approach for the preparation of experimental scenarios, is being conceived on Tore Supra, together with a new plasma control system. This paper will report on their conceptual design and give account of the preliminary results of a feasibility study currently under way in order to prepare a possible implementation on Tore Supra.

Tore Supra routinely addresses the physics and technology of very long-duration plasma discharges, thus bringing precious information on critical issues of long pulse operation of ITER. A new ITER relevant lower hybrid current drive (LHCD) launcher has allowed coupling to the plasma a power level of 2.7 MW for 78 s, corresponding to a power density close to the design value foreseen for an ITER LHCD system. In accordance with the expectations, long distance (10 cm) power coupling has been obtained. Successive stationary states of the plasma current pro le have been controlled in real-time featuring (i) control of sawteeth with varying plasma parameters, (ii) obtaining and sustaining a 'hot core' plasma regime, (iii) recovery from a voluntarily triggered deleterious magnetohydrodynamic regime. The scrape-off layer (SOL) parameters and power deposition have been documented during L-mode ramp-up phase, a crucial point for ITER before the X-point formation. Disruption mitigation studies have been conducted with massive gas injection, evidencing the difference between He and Ar and the possible role of the q = 2 surface in limiting the gas penetration. ICRF assisted wall conditioning in the presence of magnetic eld has been investigated, culminating in the demonstration that this conditioning scheme allows one to recover normal operation after disruptions. The effect of the magnetic eld ripple on the intrinsic plasma rotation has been studied, showing the competition between turbulent transport processes and ripple toroidal friction. During dedicated dimensionless experiments, the effect of varying the collisionality on turbulence wavenumber spectra has been documented, giving new insight into the turbulence mechanism. Turbulence measurements have also allowed quantitatively comparing experimental results with predictions by 5D gyrokinetic codes: numerical results simultaneously match the magnitude of effective heat diffusivity, rms values of density uctuations and wavenumber spectra. A clear correlation between electron temperature gradient and impurity transport in the very core of the plasma has been observed, strongly suggesting the existence of a threshold above which transport is dominated by turbulent electron modes. Dynamics of edge turbulent uctuations has been studied by correlating data from fast imaging cameras and Langmuir probes, yielding a coherent picture of transport processes involved in the SOL.

R. Abgrall,1 M. H. Achard, J. Adam, G. Agarici, E. Agostini, M. Airaj, F. Albajar-Vinas, L. Allegretti, J. P. Allibert, J. C. Alliez, A. Allouche,2 J. Andreoletti, J. M. Ane, P. Angelino, T. Aniel, G. Antar, N. Arcis, A. Argouarch, C. Arnas,2 G. Arnoux, R. Arslanbekov, J. F. Artaud, E. Asp, S. Assas, G.Attuel, R.Aymar,A.Azeroual, S. Balme, O. Barana, B. Bareyt, V. Basiuk, M. Basko, P. Bayetti, L. Baylor,3 B. Beaumont, R. Becherer, A. Becoulet, M. Becoulet, L. Begrambekov,4 S. Benkadda,2 F. Benoit, V. Bergeaud, G. Berger-By, S. Berio, P. Bernascolle, N. Bernier, M. Berroukeche, B. Bertrand, D. Bessette, P. Beyer,2 P. Bibet, J. Bizzaro, P. Blanchard,5 J. Blum,6 S. Boddeker, D. Boilson,7 G. Bon Mardion, P. Bonnel, X. Bonnin, J. Boscary, G. Bosia, J. M. Bottereau, F. Bottiglioni, H. Bottollier-Curtet, C. Bouchand, G. Bouligand, F. Bouquey, C. Bourdelle, R. Bregeon, F. Bremond,8 S. Bremond, C. Breton, M. Breton, C. Brosset, R. Brugnetti, J. L. Bruneau, J. Bucalossi, R. V. Budny,9 Y. Buravand, C. Bush,3 M. N. Bussac,10 A. Cambe, H. Capes, J. J. Capitain, P. Cara, J. L. Carbonnier, S. Carpentier, J. Carrasco, A. Casati, O. Chaibi, C. Chamouard, M. Chantant, P. Chappuis, D. Chatain, E. Chatelier, M. Chatelier, J. H. Chatenet,10 X. P. Chen, L. Cherigier, G. Chevet, L. Chiarazzo, D. Ciazynski, G. Ciraolo, F. Cismondi, F. Clairet, J. Clary, C. Clement, L. Colas, N. Commaux, E. Corbel, J. J. Cordier, Y. Corre, L. Costanzo, A. Cote, J. P. Coulon, L. Courtois, X. Courtois, B. Couturier, J. P. Crenn, P. Cristofani, N. Crouseilles,11 O. Czarny, P. Da Silva Rosa, C. Darbos, G. Darmet, M. Davi, R. Daviot, H. De Esch, B. De Gentile, J. C. De Haas, E. De La Cal, C. De Michelis, C. Deck, J. Decker, P. Decool, P. Degond, R. Dejarnac, E. Delchambre, E. Delmas, L. Delpech, H. Demarthe, M. Dentan, G. Depret, P. Deschamps, C. Desgranges, P. Devynck, L. Doceul, N. Dolgetta, C. Doloc, Y. Dong,12 P. Dore, D. Douai, H. Dougnac, H. W. Drawin, J. Druaux, M. Druetta,13 F. Dubois, M. Dubois, N. Dubuit, J. L. Duchateau, T. Dudok de Wit, E. Dufour, R. Dumont, G. Dunand, L. Dupas, Y. Duran,14 A. Durocher, D. Edery, A. Ekedahl, D. Elbeze, L. G. Eriksson, D. Escande,2 A. Escarguel, F. Escourbiac, T. Evans,15, F. Faisse, G. Falchetto, T. Fall, M. Farge,16 J. L. Farjon, E. Faudot,17 P. Fazilleau, N. Fedorczak, C. Fenzi-Bonizec, J. R. Ferron,15 I. Fidone, C. Figarella, E. Fleurence, I. Fleury, M. Fois, C. Forrest,15 C. A. Foster,3 S. Fouquet, C. Fourment, D. Fraboulet, P. Francois, B. Franel, D. Frigione,18 P. Froissard, G. Fubiani, V. Fuchs,14 M. Fumelli, B. Gagey, V. Galindo, D. Gambier, L. Garampon, X. Garbet, R. Garbil, J. Garcia, J. L. Gardarein, L. Gargiulo, P. Garibaldi, P. Garin, E. Gauthier, A. Geraud, T. Gerbaud, F. Gervais,19 M. Geynet, P. Ghendrih, T. Gianakon, R. Giannella, C. Gil, J. P. Girard, G. Giruzzi, L. Godbert-Mouret,2 P. Gomez, M. Goniche, A. Gordeev,4 G. Granata, V. Grandgirard, R. Gravier, B. Gravil, M. Gregoire, S. Gregoire, P. Grelot, D. Gresillon,19 C. Grisolia, G. Gros, *Other affiliations are those at the time the collaborations began. 1INRIA-CNRS, Université Sciences et Technologies, Bordeaux, France 2Physique des Interactions Ioniques et Moléculaires ~PIIM !, Université de Provence, Centre Universitaire St Jérôme, 13397 Marseille Cedex 20, France 3Oak Ridge National Laboratory, Fusion Energy Division, P.O. Box 2009, Oak Ridge, Tennessee 37831-8070, USA 4Moscow Physics and Engineering Institute ~MEPhI!, 31 Karhirskoe Sh, 115409 Moscow, Russian Federation 5Centre de Recherche en Physique des Plasmas, Association EURATOM-Confédération Suisse, Ecole Polytechnique Fédérale, PPB-Ecublens, 1015 Lausanne, Suisse 6Université Joseph Fourier, Grenoble I, B.P. 53, 38041 Grenoble Cedex 9, France 7School of Physical Sciences, Dublin City University, Glasnevin, EI-Dublin 9, Ireland 8INRIA Sophia-Antipolis, 2004 Route des Lucioles, B.P. 93, 06902 Nice-Sophia-Antipolis, France 9Princeton Plasma Physics Laboratory, James Forrestal Campus, Princeton, New Jersey 08543, USA 10Centre de Physique Théorique, Ecole Polytechnique, 91128 Palaiseau, France 11IRMA, Université Louis Pasteur, Strasbourg, France 12Southwestern Institute of Physics, Chengdu 610041, China 13Laboratoire TSI, Université Jean Monnet, 42023 St-Etienne, France 14Association EURATOM-IPP.CR, Institute of Plasma Physics AS CR, Za Slovankou 3, 182 21 Praha 8, Czech Republic 15General Atomics, P.O. Box 85608, San Diego, California 921865608, USA 16LMD, Ecole Normale Supérieure, 75 Paris, France 17LPMIA, Université Henri Poincaré, Nancy 1, B.P. 239, 54506 Vandœuvre Cedex, France 18Associazione EURATOM-ENEAsulla Fusione, C.R. Frascati, Roma, Italy 19Laboratoire de Physique et Technologie des Plasmas ~LPTP!, Ecole Polytechnique, 91128 Palaiseau, France

The main results of the Tore Supra experimental programme in the years 2007–2008 are reported. They document significant progress achieved in the domain of steady-state tokamak research, as well as in more general issues relevant for ITER and for fusion physics research. Three areas are covered: ITER relevant technology developments and tests in a real machine environment, tokamak operational issues for high power and long pulses, and fusion plasma physics. Results presented in this paper include test and validation of a new, load-resilient concept of ion cycotron resonance heating antenna and of an inspection robot operated under ultra-high vacuum and high temperature conditions; an extensive experimental campaign (5 h of plasma) aiming at deuterium inventory and carbon migration studies; real-time control of sawteeth by electron cyclotron current drive in the presence of fast ion tails; ECRH-assisted plasma start-up studies; dimensionless scalings of transport and turbulence; transport experiments using active perturbation methods; resistive and fast-particle driven MHD studies. The potential role of Tore Supra in the worldwide fusion programme before the start of ITER operation is also discussed.