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Before the installation of the first ICRF launcher in WEST, dedicated RF, cold and hot leak tests have been performed in the TITAN test bed [ 1 , 2 ] (Bernard et al., 2011a,b). All the water circuits have been controlled in order to avoid any in-vessel leak. The impedance matching has been checked at low level (mW range) and the high RF voltage standoff has been validated at the nominal value of 27 kV peak. During the WEST C3a campaign, the commissioning of the first antenna has been successfully performed. About 0.6 MW of power has been coupled to the plasma, and the launcher’s load-resilience has been proved. more...

International audience; In this study, Triton X-100 was used as the WS2 dispersion agent in the AueCo cyanide electrolyte to deposit AueCo/WS2 composite coatings. Probe sonication was applied to exfoliate the commercial WS2 powders to produce thinner and smaller WS2 flakes, which improved the stability of the WS2 particles in the electrolyte. According to the electrochemical analyses, the effects of adding Triton X-100 and WS2 particles to the electroplating process were investigated. Through material characterizations, WS2 particles were proved to be compounded into the AueCo matrix and showed clearly {002} preferred orientation due to their flake structures. Tribological tests were performed under dry condition in 10�3 Pa vacuum against stainless steel 316L balls with diameters of 3 mm and a normal contact force of2 N. The AueCo/WS2 composite coatings that developed showed the minimum coefficient of friction and wear rate of 0.05 and 8 � 10�6 mm3/N$m, which are 5 times and 3 times lower than the AueCo reference coating, respectively more...

Within the large scale fusion experimental device ITER, Ion Cyclotron Resonance Heating (ICRH) system is one of the three heating systems which will supply total heating power of 20 MW (40-55 MHz) up to one hour operation. Radio-Frequency (RF) contacts are integrated within the antennas for assembly and operation considerations, which will face extremely harsh service conditions, including neutron irradiation, heavy electrical loads (RF current reaches up to 2 kA with a linear current density of 4.8 kA/m), high thermal loads and also long-duration vacuum baking at 250°C before each experimental plasma campaign. CuCrZr and 316L steel have been shown to be proper base candidate materials for ITER RF contact louvers and conductors respectively. However, in order to limit the wear and the diffusion phenomena at the RF contact as well as to reduce the contact resistance, functional protective layers should be developed. The aim of this work is to investigate Au-Ni and Rh functional layers, electroplated on CuCrZr and 316L respectively. The efficiency of the Au-Ni/Rh coated pairs was evaluated through thermal ageing diffusion tests, using EDS cross-section mapping and XRD techniques. Wear and electrical contact performances of the Au-Ni/Rh original and thermally aged pairs have also been deeply studied on a dedicated tribometer operated at ITER relevant conditions. more...

The ITER Ion Cyclotron Resonance Heating (ICRH) system is designed to couple to the plasma 20 MW of RF power from two antennas in the 40-55 MHz frequency range during long pulses of up to 3600 s and under various plasma conditions with Edge Localized Modes. Radio-Frequency (RF) contacts are integrated within the ITER ICRH launcher in order to ensure the RF current continuity and ease the mechanical assembly by allowing the free thermal expansion of the Removable Vacuum Transmission Line coaxial conductors during RF operations or during 250{\textdegree}C baking phases. A material study has been carried out to determine which materials and associated coatings are relevant for RF contacts application in ITER. In parallel, RF tests have been performed with a new prototype of Multi-Contact (r) LA-CUT/0,25/0 contacts made of silver-coated CuCrZr louvers. During these tests on a RF vacuum resonator, currents between 1.2 kA and 1.3 kA peak have been reached a few tens of times in steady-state conditions without any visible damage on the louvers. A final 62MHz pulse ending in a 300s flat top at 1.9kA resulted in severe damage to the contact. In addition, a test bed which performs sliding test cycles has been built in order to reproduce the wear of the contact prototype after 30 000 sliding cycles on a 3 mm stroke at 175{\textdegree}C under vacuum. The silver coating of the louvers is removed after approximately a hundred cycles whilst, to the contrary, damage to the CuCrZr louvers is relatively low., Fusion Engineering and Design, Elsevier, A Para{\^i}tre more...

International audience; Compounding Au-Ni with carbon (C) lubricants is a feasible approach to improve its mechanical properties and wear performance. In this study, 3.5 µm-thick Au-Ni/C nanocomposite coatings with a low residual stress on CuCrZr substrates by magnetron sputtering were developed. Face-centered cubic and hexagonal close-packed stacking structures were both confirmed in the composite coatings based on transmission electron microscopy and X-ray diffraction analyses. Amorphous C (a-C) was confirmed to be the structure of C in the composite coatings, and its graphitization transition with an increase in the C content was validated by X-ray photoemission spectra and Raman spectroscopy. By compounding 0.88 wt.% a-C, the hardness of the Au-Ni/a-C coating reached 400 HV, which is twice higher than that of the Au-Ni coating. The electrical resistivity of the Au-Ni/a-C coating is relatively stable with an increase in the a-C content. As graphitization occurred on the wear track, the produced composite coatings showed a minimum wear rate of 2.2×10$^{-6}$ mm$^3$ /N·m under atmospheric conditions, which is half that of the Au-Ni reference coating. Under vacuum, the wear performance of the produced Au-Ni/a-C composite coatings was similar to that of the Au-Ni reference coating. more...

International audience; Rhodium (Rh) coating on CuCrZr substrate is a promising material option for optical, structural and electrical applications on nuclear fusion reactors. For these applications, Rh coated CuCrZr components subject to long time of thermal ageing due to pre-treatment or normal operation condition. In this paper, both finite element method (FEM) and experimental method were applied to investigate the effects of thermal ageing on mechanical performance of Rh coating after 250 °C, 500 h baking in vacuum. Based on FEM analysis, thermal stresses which concentrate at Rh coating interface is the main source of cracking, and such stresses can be minimized efficiently by introducing a 0.5 μm Au interlayer into the coating layer structure. According to thermal ageing experiments, through-thickness cracking in the Rh coating due to thermal stress releasing and voids generated at the Rh bonding interface caused by Kirkendall effect were the main micro-structure changes in the coating system. The solid-solution hardening caused by significant Cu diffusion into Rh is the dominant factor that affected the Rh coating's hardness. The existing of large amount of cracks in the Rh coating and voids at the Rh coating interface deteriorated the adhesion performance of Rh on CuCrZr substrate by 30%. more...

Radio-frequency (RF) contacts—which are an example of electrical contacts—are commonly employed on accelerators and nuclear fusion experimental devices. RF contacts with a current load of 2 kA for steady-state operation were designed for application to the International Thermonuclear Experimental Reactor (ITER) device. In contrast to the typical working conditions of general commercial electrical contacts, those of RF contacts employed on fusion devices include high vacuum, high temperature, and neutron radiation. CuCrZr is currently of interest as a base material for the manufacture of louvers of RF contacts, which has excellent thermal and electrical properties and has low creep rate at 250 °C. In this study, a hard Au coating (Au-Ni) was electroplated on CuCrZr samples and the samples were then subjected to thermal aging treatment at 250 °C for 500 h in order to simulate the vacuum-commissioning process of the ITER. The effects of thermal aging on the hardness, elastic modulus, crystallite size, and compositions of the coating were investigated via microstructural and mechanical characterizations of the coating material. Metal atom migration in different coating layers during thermal aging was characterized and evaluated via scanning electron microscopy/energy dispersive X-ray spectroscopy observations of the cross-sectional surfaces, and the obtained results could be used to directly select the coating thickness for the final RF contact component. The contact resistance—an important parameter of the RF contact—was measured in a dedicated testbed built to simulate fusion reactor conditions between CuCrZr pins and stainless steel plates coated with Au-Ni and Rh, respectively. Radio-frequency (RF) contacts-which are an example of electrical contacts-are commonly employed on accelerators and nuclear fusion experimental devices. RF contacts with a current load of 2 kA for steady-state operation were designed for application to the International Thermonuclear Experimental Reactor (ITER) device. In contrast to the typical working conditions of general commercial electrical contacts, those of RF contacts employed on fusion devices include high vacuum, high temperature, and neutron radiation. CuCrZr is currently of interest as a base material for the manufacture of louvers of RF contacts, which has excellent thermal and electrical properties and has low creep rate at 250 {\textdegree}C. In this study, a hard Au coating (Au-Ni) was electroplated on CuCrZr samples and the samples were then subjected to thermal aging treatment at 250 {\textdegree}C for 500 h in order to simulate the vacuum-commissioning process of the ITER. The effects of thermal aging on the hardness, elastic modulus, crystallite size, and compositions of the coating were investigated via microstructural and mechanical characterizations of the coating material. Metal atom migration in different coating layers during thermal aging was characterized and evaluated via scanning electron microscopy/energy dispersive X-ray spectroscopy observations of the cross-sectional surfaces, and the obtained results could be used to directly select the coating thickness for the final RF contact component. The contact resistance-an important parameter of the RF contact-was measured in a dedicated testbed built to simulate fusion reactor conditions between CuCrZr pins and stainless steel plates coated with Au-Ni and Rh, respectively. more...

Embedded RF contacts are integrated within the ITER ICRH launcher to allow assembling, sliding and to lower the thermo-mechanical stress. They have to withstand a peak RF current up to 2.5 kA at 55 MHz in steady-state conditions, in the vacuum environment of themachine.The contacts have to sustain a temperature up to 250{\textdegree}Cduring several days in baking operations and have to be reliable during the whole life of the launcher without degradation. The RF contacts are critical components for the launcher performance and intensive R&D is therefore required, since no RF contactshave so far been qualified at these specifications. In order to test and validate the anticipated RF contacts in operational conditions, CEA has prepared a test platform consisting of a steady-state vacuum pumped RF resonator. In collaboration with ITER Organization and the CYCLE consortium (CYclotronCLuster for Europe), an R&D program has been conducted to develop RF contacts that meet the ITER ICRH launcher specifications. A design proposed by CYCLE consortium, using brazed lamellas supported by a spring to improve thermal exchange efficiency while guaranteeing high contact force, was tested successfully in the T-resonator up to 1.7 kA during 1200 s, but failed for larger current values due to a degradation of the contacts. Details concerning the manufacturing of the brazed contacts on its titanium holder, the RF tests results performed on the resonator and the non-destructive tests analysis of the contacts are given in this paper., Comment: Fusion Engineering and Design, Elsevier, 2015, Available online 21 April 2015 more...

The WEST (Tungsten (W) Environment in Steady-state Tokamak) is an upgrade of Tore-Supra (TS) which aims it into an X -point magnetic configuration tokamak equipped with an actively cooled tungsten divertor. To be a platform of ITER technologies of high heat flux components testing, three sets of Ion Cyclotron Resonant Heating (ICRH) antennas have been designed to inject 9 MW during 30 s or 3 MW during 1000 s. The antenna design is based on a load resilient prototype successfully tested in Tore Supra in 2007. In order to allow continuous-wave (CW) operations, the mechanical design of the WEST ICRH antenna is emphasized on its cooling performances by designing fully active cooling structure. Two kinds of cooling water loops are used, with temperature and pressure of 70 °C/30 bar and 25 °C/5.2 bar, respectively. The hot water loop is used for the Faraday screen (FS) and the housing box (HB), while the cold water loop is used for the straps, the matching capacitors and the impedance transformer. To enhance the heat removal ability and control the pressure drop, the cooling channels in the FS and HB are drilled directly and parallel connected as much as possible. By performing the hydraulic–thermal analysis, the lack of cooling efficiency was found in the front face of lateral collector where 1 MW/m 2 is imposed and fluid dead zones were found in some of the bars. After optimization, the cooling performance of the cooling circuit increased significantly. With a mass flow rate of 2.5 kg/s, the total pressure drop is 3.1 bar, and the peak temperatures on the FS and HB are 500 °C and 261 °C, respectively. Besides, no cavitation is found in the total cooling circuit. more...

29th Symposium on Fusion Technology (SOFT), Prague, CZECH REPUBLIC, SEP 05-09, 2016; International audience; One of the key missions of the Ion Cyclotron Resonant Heating (IRCH) system for WEST is to provide sufficient RF heating power in order to obtain a heat flux on the divertor target of 10 MW/m(2) during 1000 s and 20 MW/m(2) during a few tens of seconds. Based on the experience acquired in Tore Supra, the ICRH system has been upgraded for long pulse operation and Edge Localized Modes (ELM) resilience. To achieve this performance, three antennas have been designed through a European collaboration and are now under fabrication at CAS/ASIPP, at the Keye Company, Hefei, in China, within the framework of the Associated Laboratory IRFM-ASIPP. This paper describes the electrical and mechanical design of the antenna, together with the main manufacturing steps and leak test procedure used for validating the water-cooled components. Accessibility and maintenance studies on WEST have been performed with the help of virtual reality. The first ICRH antenna was delivered at Cadarache in July 2016, and is foreseen to be installed on WEST in 2017. (C) 2017 Elsevier B.V. All rights reserved. more...

International audience; ITER is a large scale fusion experimental device under construction in Cadarache (France) intended to prove the viability of fusion as an energy source. Ion Cyclotron Resonance Heating (ICRH) system is one of the three heating systems which will supply total heating power of 20 MW (40-55 MHz) up to one hour of operation. Radio-Frequency (RF) contacts are integrated within the antennas for assembly and operation considerations, which will face extremely harsh service conditions, including neutron irradiation, heavy electrical loads (RF current reaches up to 2 kA with a linear current density of 4.8 kA/m) and high thermal loads. Based on the thermal analysis, the contact resistance is expected to be lower than 7 mΩ to keep the maximum temperature on the louvers lower than 250°C. Few weeks of vacuum (~10$^{-5}$ Pa) baking at 250°C for outgassing is expected before each plasma experimental campaign, under which the RF contact materials' mechanical properties change and diffusion phenomena between different materials are inevitable. CuCrZr and 316L are proper base materials for ITER RF contact louvers and conductors respectively. In order to improve the RF contact's wear and corrosion resistivity as well as to reduce the contact resistance, Au-Ni and Rh functional layers could be electroplated on CuCrZr and 316L accordingly. The application of the Au-Ni/Rh coating pairs is assessed through the thermal ageing and diffusion tests. Wear and electrical contact performances of the Au-Ni/Rh pairs are deeply studied on a dedicated tribometer operated at ITER relevant conditions. more...

This year Tore-Supra celebrated its 25 years of operation. During this long time, a number of technologies have been developed. First of all, it was mandatory to develop reliable superconducting magnets at ∼1.8 K, with superfluid helium as an efficient coolant. For the production of steady state discharge, three types of radio frequency (RF) additional heating systems have been developed: 1) lower hybrid current drive; 2) ion cyclotron resonance heating; and 3) electron cyclotron resonance heating. To cope with long lasting discharges (up to 380 s × 2.8 MW) and large RF additional heating power (12.3 MW × 3 s), actively cooled (AC) plasma facing components were deployed in Tore-Supra for the first time in a tokamak environment. Tore-Supra is now being modified into a D-shape axisymmetric tokamak with AC tungsten main chamber walls and a divertor, the WEST project (W-for tungsten-environment in steady-state tokamak). This new facility has the objective to offer ITER a test bed for validating the relevant AC metallic technologies in D-shape H-mode plasmas. In contrast to other metallic devices, such as JET and ASDEX Upgrade, WEST will rely only on the RF additional power systems. A set of plasma scenarios have been identified, ranging from a high total RF power scenario up to 15 MW in 30 s, to a high fluence scenario of 1000 s with up to 10 MW of injected RF power. These scenarios are able to reproduce ITER relevant conditions of steady state heat loads of 10-20 MW/m2, to test tungsten AC divertor technologies with relevant power heat fluxes and particle fluence. more...

Three new ion cyclotron resonance heating (ICRH) launchers have been designed for the WEST project (W-Tungsten Environment in Steady-state Tokamak) in order to operate at 3 MW/launcher for 30 s and 1 MW/launcher for 1000 s on H-mode plasmas. These new launchers will be to date the first ICRH launchers to offer the unique combination of continuous-wave (CW) operation at high power and load tolerance capabilities for coupling on H-mode edge. The radio-frequency (RF) design optimization process has been carried out using full-wave electromagnetic solvers combined with electric circuit calculations. Cavity modes occurring between the launchers structures and the vacuum vessel ports have been evaluated and cleared out. more...

SIDON (SImulator of raDiO-frequency Networks) is an in-house developed Radio-Frequency (RF) network solver that has been implemented to cross-validate the design of WEST ICRF launchers and simulate their impedance matching algorithm while considering all mutual couplings and asymmetries. In this paper, the authors illustrate the theory of SIDON as well as results of its calculations. The authors have built time-varying plasma scenarios (a sequence of launchers front-faces L-mode and H-mode Z-matrices), where at each time step (1 millisecond here), SIDON solves the RF network. At the same time, when activated, the impedance matching algorithm controls the matching elements (vacuum capacitors) and thus their corresponding S-matrices. Typically a 1-second pulse requires around 10 seconds of computational time on a desktop computer. These tasks can be hardly handled by commercial RF software. This innovative work allows identifying strategies for the launchers future operation while insuring the limitations on the currents, voltages and electric fields, matching and Load-Resilience, as well as the required straps voltage amplitude/phase balance. In this paper, a particular attention is paid to the simulation of the launchers behavior when arcs appear at several locations of their circuits using SIDON calculator. This latter work shall confirm or identify strategies for the arc detection using various RF electrical signals. One shall note that the use of such solvers in not limited to ICRF launchers simulations but can be employed, in principle, to any linear or linearized RF problem. more...

The longstanding expertise of the Tore Supra team in long pulse heating and current drive with radiofrequency (RF) systems will now be exploited in the WEST device (tungsten-W Environment in Steady-state Tokamak) [1]. WEST will allow an integrated long pulse tokamak programme for testing W-divertor components at ITER-relevant heat flux (10-20 MW/m2), while treating crucial aspects for ITER-operation, such as avoidance of W-accumulation in long discharges, monitoring and control of heat fluxes on the metallic plasma facing components (PFCs) and coupling of RF waves in H-mode plasmas. Scenario modelling using the METIS-code shows that ITER-relevant heat fluxes are compatible with the sustainment of long pulse H-mode discharges, at high power (up to 15 MW / 30 s at IP = 0.8 MA) or high fluence (up to 10 MW / 1000 s at IP = 0.6 MA) [2], all based on RF heating and current drive using Ion Cyclotron Resonance Heating (ICRH) and Lower Hybrid Current Drive (LHCD). This paper gives a description of the ICRH and LH... more...

International audience; The design of the WEST (Tungsten-W Environment in Steady-state Tokamak) Ion cyclotron resonance heating antennas is based on a previously tested conjugate-T Resonant Double Loops prototype equipped with internal vacuum matching capacitors. The design and construction of three new WEST ICRH antennas are being carried out in close collaboration with ASIPP, within the framework of the Associated Laboratory in the fusion field between IRFM and ASIPP. The coupling performance to the plasma and the load-tolerance have been improved, while adding Continuous Wave operation capability by introducing water cooling in the entire antenna. On the generator side, the operation class of the high power tetrodes is changed from AB to B in order to allow high power operation (up to 3 MW per antenna) under higher VSWR (up to 2:1). Reliability of the generators is also improved by increasing the cavity breakdown voltage. The control and data acquisition system is also upgraded in order to resolve and react on fast events, such as ELMs. A new optical arc detection system comes in reinforcement of the V r /V f and SHAD systems. more...

Is the town of Compiègne, in Northern France, a myth as Grenoble has been told ? The urban imaginary hides several social spaces. In the 80's and 90's, the local social geography was simplified. The opposition between centre and periphery becomes harder. The social and spatial differences inside the lower middle class are inverted. The integration of the immigrants of Picardy is executed in an opposite place, in the centre and not more in the periphery. This new social geography has relation with urban regulations. After all, the analysis discovers a richer urban imaginary. The modern idea of "several social worlds" is a theoretical way in order to explore, to articulate urban imagina¬ ry and social spaces., L'imaginaire compiègnois recouvre une pluralité d'espaces sociaux. Au cours des années 1980 et 1990, la géographie sociale se simplifie. L'opposition centre-périphérie liée aux ressources économiques, sociales et scolaires se durcit. Corrélativement, les différenciations socio-spatiales de la petite bourgeoise locale s'inversent : l'intégration des immigrants picards s'effectue désormais au centre, et non plus par la périphérie. Cette recomposition de la géographie sociale pose la question des modes de régulation urbaine. In fine, l'analyse découvre un imaginaire enrichi. L'idée de "pluralité des mondes sociaux" constitue une entrée théorique pour explorer, confronter imaginaire urbain et espaces sociaux., Bernard Alain JM. Compiègne, entre imaginaire urbain et pluralité des mondes sociaux. In: Hommes et Terres du Nord, 1999/2. Etudes picardes. Hommage à Pierre Limouzin. pp. 75-84. more...

The Ion Cyclotron Heating and Current Drive (IC H & CD) system for ITER will provide Radio frequency (RF) heating and current drive to the ITER plasma. This system is designed to provide 20 MW into the plasma using frequencies in the range of 40 MHz to 55 MHz, which could be upgraded to 40 MW in future. This paper presents the recent development of the IC H&CD system configuration in the ITER Tokamak complex & auxiliary buildings with developed interfaces. more...

A contribution to the study of nutrition in urban milieus : meat-consumption in Amiens. Through the study of one exemplifying instance medium-sized towns in France — Amiens —, the writer attemps to work out a specific methodology pertaining to the examination of meat-consumption in urban milieus that takes into account both statical and dynamic approaches. Through the diachronical analysis of the meat-diets in Amiens from 1830 onward one discerns a pattern which, close to hub and spoke city-models rests on two kinds of motions : reciprocal actions of town versus country, town-center versus pericenter., À travers l'étude d'un cas représentatif des villes moyennes françaises, — l'exemple amiénois —, l'auteur tente de définir une méthodologie spécifique à l'étude des consommations carnées en milieux urbains qui concilie approches statique et dynamique. L'analyse diachronique des habitudes carnées amiénoises à partir de 1830 découvre une structure qui, proche des modèles radioconcentriques, repose sur deux types de flux : interactions ville-campagne, centre ville-péricentre., Bernard Alain J. M. Contribution à l'étude des milieux alimentaires urbains. La consommation de viande à Amiens. In: Annales de Géographie, t. 88, n°487, 1979. pp. 315-350. more...

Since 1975, Compiègne knows a new expansion, justified by retertiarisation of the local economy. Growth factors are external, strongly tied to public authority. They are also internal, as attested by dynamism of small or medium companies. Emergence of the Compiègne's technopole results of both processus, converting the old imperial town into a technopolis., Depuis 1975, Compiègne connaît une nouvelle expansion fondée sur la retertiairisation de l'économie locale. Les facteurs de la croissance sont exogènes, fortement liés à la puissance publique. Ils sont aussi endogènes, comme l'atteste le dynamisme des Pme. L'émergence du technopole compiègnois participe de ces deux processus, transformant la vieille cité impériale en technopolis., Bernard Alain Jean Michel. Compiègne, une nouvelle dynamique : de la Carlopolis à la Technopolis. In: Hommes et Terres du Nord, 1988/4. Picardie. pp. 203-215. more...

The question of food consumption brings forward organic, economic, psychological and social aspects which, although intinately linked, are usually treated separately by the biological and the social and economic sciences. Although considered necessary, constant contact and combined research projects are not easy to organize. The biologists of nutrition, the first to be aware of the problem, have tried to solve it, but without any lasting success. Geographers are giving an account of their own efforts in this field., La consommation alimentaire a des aspects organiques, économiques, psychologiques, sociaux interdépendants et étudiés généralement isolément par les sciences biologiques et les sciences économiques et sociales. Bien qu'estimés nécessaires, des contacts et des projets de recherche interdisciplinaires ne sont pas simples à organiser. Conscients du problème, les biologistes de la nutrition les ont tentés sans succès durable. Des géographes rendent compte de leurs efforts en ce domaine., Bernard Alain J. M., Salles Paulette, Thouvenot Claude. Consommation alimentaire : une orientation interdisciplinaire. In: Annales de Géographie, t. 89, n°493, 1980. pp. 258-272. more...