Operating a full tungsten actively cooled tokamak: overview of WEST first phase of operation

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

Feature Extraction for Cortical Sulci Identification

International audienceThe use of PET in quantitative measurement of brain activity requires the superimposition of some anatomical data coming from other sources, like MRI. In the frame of structural and anatomical data matching for a great number of patients, we developed a method for the automatic identification of cortical sulci on 3D MR images. The knowledge used is automatically extracted from a database containing a few pictures where sulci have been previously recognized. Proportional correction mechanisms, based on Talairach's grid, are proposed. They intend to adapt sulci statistical models to the particular features of any brain, in order to make the recognition easier. Our identification method is efficient and robust for the superficial part of six major sulci

Achievements on Engineering and Manufacturing of ITER First Mirrors Mock-Ups

Most of ITER optical diagnostics will be equipped with in-vessel metallic mirrors as plasma viewing components. These mirrors will be exposed to severe plasma environment which implies important research and developments on their design and manufacturing. Therefore investigations on engineering and manufacturing have been carried out on diagnostic mirrors towards the development of full-scale stainless steel and TZM (Mo-based alloy) ITER mirrors. Several micrometers in thickness of rhodium and molybdenum reflective coating layers have been deposited on the components to insure long-lasting of the mirrors exposed to an environment that could be dominated by neutral flux (charge-exchange). Three major issues have been addressed and reported in this paper: First, investigations have been performed on the design and manufacturing of the mirror integrated cooling system, so that the optical surface deformation due to radiations from the plasma and nuclear heating is limited. For the thermo mechanical design of the mock-ups, plasma radiation flux of 0,5 MW/m2 and neutron head load of 7 MW/m3 have been considered. Secondly, the polishing capability of full-scale (109 mm in diameter) metallic mirrors has been demonstrated: the mock ups Surface Front Error is lower than 0,1 μm Root Mean Square, and the mirrors exhibit low roughness (Ra <; 2 nm) and low surface defects (scratch width lower than 0,02 mm) after polishing. Thirdly, the manufacturing feasibility of molybdenum and rhodium thick coating layers deposited by magnetron sputtering has been evaluated. The objective of depositing layers up to 3 μm to 5 μm thick has been achieved on the mock-ups, with spectral performances reaching the theoretical values and showing high reflectivity over a large spectral range (from 400 nm to 11 μm). Finally the test campaign of the manufactured mirrors, which is being prepared in several European facilities to expose the mirrors to deuterium plasma, ELMs, neutrons, erosion and deposition conditions, is reported

Thermo-Mechanical Analysis of ITER First Mirrors and Its Use for the ITER Equatorial Visible/Infrared Wide Angle Viewing System Optical Design

ITER first mirrors (FMs), as the first components of most ITER optical diagnostics, will be exposed to high plasma radiation flux and neutron load. To reduce the FMs heating and optical surface deformation induced during ITER operation, the use of relevant materials and cooling system are foreseen. The calculations led on different materials and FMs designs and geometries (100 mm and 200 mm) show that the use of CuCrZr and TZM, and a complex integrated cooling system can limit efficiently the FMs heating and reduce their optical surface deformation under plasma radiation flux and neutron load. These investigations were used to evaluate, for the ITER equatorial port visible/infrared wide angle viewing system, the impact of the FMs properties change during operation on the instrument main optical performances. The results obtained are presented and discussed

Engineering and manufacturing of ITER first mirror mock-ups

Most of the ITER optical diagnostics aiming at viewing and monitoring plasma facing components will use in-vessel metallic mirrors. These mirrors will be exposed to a severe plasma environment and lead to an important tradeoff on their design and manufacturing. As a consequence, investigations are carried out on diagnostic mirrors toward the development of optimal and reliable solutions. The goals are to assess the manufacturing feasibility of the mirror coatings, evaluate the manufacturing capability and associated performances for the mirrors cooling and polishing, and finally determine the costs and delivery time of the first prototypes with a diameter of 200 and 500 mm. Three kinds of ITER candidate mock-ups are being designed and manufactured: rhodium films on stainless steel substrate, molybdenum on TZM substrate, and silver films on stainless steel substrate. The status of the project is presented in this paper

Study of heat flux deposition on the limiter of the Tore Supra tokamak

International audienc

WEST Physics Basis

With WEST (Tungsten Environment in Steady State Tokamak) (Bucalossi et al 2014 Fusion Eng. Des. 89 907–12), the Tore Supra facility and team expertise (Dumont et al 2014 Plasma Phys. Control. Fusion 56 075020) is used to pave the way towards ITER divertor procurement and operation. It consists in implementing a divertor configuration and installing ITER-like actively cooled tungsten monoblocks in the Tore Supra tokamak, taking full benefit of its unique long-pulse capability. WEST is a user facility platform, open to all ITER partners. This paper describes the physics basis of WEST: the estimated heat flux on the divertor target, the planned heating schemes, the expected behaviour of the L–H threshold and of the pedestal and the potential W sources. A series of operating scenarios has been modelled, showing that ITER-relevant heat fluxes on the divertor can be achieved in WEST long pulse H-mode plasmas

Investigation of steady-state tokamak issues by long pulse experiments on Tore Supra

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 turbulenc