Papers by Jean-Marcel Travère
AIP Conference Proceedings, 2008
... Gauthier, S. Gicquel, D. Guilhem, D. Hernandez, M. Jouve, C. Le Niliot, Th. Loarer, A. Martin... more ... Gauthier, S. Gicquel, D. Guilhem, D. Hernandez, M. Jouve, C. Le Niliot, Th. Loarer, A. Martin, S. Martinez, JP Martins, JB Migozzi, JC Patterlini, C. Pocheau, F. Rigollet, H. Roche, JL Sans, S. Salasca, JM Travere, C. Walker. Abstract. ...
2013 3rd International Conference on Advancements in Nuclear Instrumentation, Measurement Methods and their Applications (ANIMMA), 2013
ABSTRACT In nuclear fusion experiments, the protection system of the Plasma Facing Components (PF... more ABSTRACT In nuclear fusion experiments, the protection system of the Plasma Facing Components (PFCs) is commonly ensured by infrared (IR) thermography. Nevertheless, the surface monitoring of new metallic plasma facing component, as in JET and ITER is being challenging. Indeed, the analysis of infrared signals is made more complicated in such a metallic environment since the signals will be perturbed by the reflected photons coming from high temperature regions. To address and anticipate this new measurement environment, predictive photonic models, based on Monte-Carlo ray tracing (SPEOS®CAA V5 Based), have been performed to assess the contribution of the reflective part in the total flux collected by the camera and the resulting temperature error. This paper deals with the effects of metals features, as the emissivity and reflectivity models, on the accuracy of the surface temperature estimation. The reliability of the features models is discussed by comparing the simulation with experimental data obtained with the wide angle IR thermography system of JET-ITER like wall. The impact of the temperature distribution is studied by considering two different typical plasma scenarios, in limiter (ITER start-up scenario) and in X-point configurations (standard divertor scenario). The achievable measurement performances of IR system and risks analysis on its functionalities are discussed.
2007 IEEE International Symposium on Intelligent Signal Processing, 2007
... CONCLUSION A. Ekedahl, D. Guilhem, M. Jouve, F. Kazarian, G. Lombard, L. Millon, R. Mitteau, ... more ... CONCLUSION A. Ekedahl, D. Guilhem, M. Jouve, F. Kazarian, G. Lombard, L. Millon, R. Mitteau, P. Mollard, H. Roche, JM Travere, F. Saint-Laurent, S. Bremond, "RF Heating optimization on Tore Supra using Measuring surface temperature using JR images iS very ...
Le tokamak Tore Supra est dédié à l'étude de décharges plasma de longues durées. La surveilla... more Le tokamak Tore Supra est dédié à l'étude de décharges plasma de longues durées. La surveillance infrarouge des composants face au plasma constituant l’intérieur de la machine est un outil de sécurité essentiel. La présence de dépôts carbonés plus ou moins adhérents sur certaines zones des composants complique l’estimation du flux de chaleur incident provenant du plasma. On propose d’exploiter ici des relevés de températures infrarouges acquis in situ pour estimer les propriétés thermiques des dépôts recouvrant le plancher de la machine, puis d’appliquer un calcul de flux adapté dans ces zones en utilisant la méthode des quadripôles thermiques.
None. Consists of a list of team members and affiliations.
Lecture Notes in Computer Science, 2011
2009 IEEE Intrumentation and Measurement Technology Conference, 2009
ANIMMA 2011 - Proceedings: 2nd International Conference on Advancements in Nuclear Instrumentation, Measurement Methods and their Applications, 2011
Review of Scientific Instruments, 2010
During operation of present fusion devices, the Plasma Facing Components (PFCs) are exposed to hi... more During operation of present fusion devices, the Plasma Facing Components (PFCs) are exposed to high heat fluxes. Understanding and preventing overheating of these components during long pulse discharges is a crucial safety issue for future devices like ITER. Infrared digital cameras interfaced with complex optical systems have become a routine diagnostic to measure surface temperatures in many magnetic fusion devices. Due to the complexity of the observed scenes and the large amount of data produced, the use of high computational performance hardware for real-time image processing is then mandatory to avoid PFC damages. At Tore Supra, we have recently made a major upgrade of our real-time infrared image acquisition and processing board by the use of a new Field Programmable Gate Array (FPGA) optimized for image processing. This paper describes the new possibilities offered by this board in terms of image calibration and image interpretation (abnormal thermal events detection) compared to the previous system.
Review of Scientific Instruments, 2012
Infrared (IR) thermography systems are mandatory to ensure safe plasma operation in fusion device... more Infrared (IR) thermography systems are mandatory to ensure safe plasma operation in fusion devices. However, IR measurements are made much more complicated in metallic environment because of the spurious contributions of the reflected fluxes. This paper presents a full predictive photonic simulation able to assess accurately the surface temperature measurement with classical IR thermography from a given plasma scenario and by taking into account the optical properties of PFCs materials. This simulation has been carried out the ITER-like wide angle infrared camera view of JET in comparing with experimental data. The consequences and the effects of the low emissivity and the bidirectional reflectivity distribution function used in the model for the metallic PFCs on the contribution of the reflected flux in the analysis are discussed.
Review of Scientific Instruments, 2010
In nuclear fusion experiments, the plasma facing components are exposed to high heat fluxes and i... more In nuclear fusion experiments, the plasma facing components are exposed to high heat fluxes and infrared (IR) imaging diagnostics are routinely used for surveying their surface temperature for preventing damages. However the future use of metallic components in the ITER tokamak adds complications in temperature estimation. Indeed, low and variable emissivity of the observed surface and the multiple reflections of the light coming from hot regions will have to be understood and then taken into account. In this paper, a realistic photonic modeling based on Monte Carlo ray-tracing codes is used to predict the global response of the complete IR survey system. This also includes the complex vessel geometry and the thermal and optical surface properties using the bidirectional reflectivity distribution function that models the photon-material interactions. The first results of this simulation applied to a reference torus are presented and are used as a benchmark to investigate the validit...
Review of Scientific Instruments, 2010
The problem of light reflection has been raised as a high priority issue for optical diagnostics ... more The problem of light reflection has been raised as a high priority issue for optical diagnostics in next step fusion devices where metallic wall environment will generate significant perturbations in the diagnostics measurements. Tore Supra is a large size tokamak equipped with water-cooled stainless-steel panels used to sustain the plasma long shot radiations. These panels are highly reflective and affect significantly optical systems. In particular, we show that the infrared imaging diagnostic, which surveys the plasma facing component surface temperature for safety purposes, can give incorrect information due to reflected light coming from the bottom limiter. In the visible range, motional Stark effect and Zeff measurements experience important drifts during the plasma heating phases due to parasitic light coming from the limiter, but also from the plasma itself when the viewing lines are facing the reflecting walls. In the next step fusion devices such as ITER, the possibility t...
Review of Scientific Instruments, 2012
ITER first mirrors (FMs), as the first components of most ITER optical diagnostics, will be expos... more 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.
Nuclear Fusion, 2011
Tore Supra routinely addresses the physics and technology of very long duration plasma discharges... more 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 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 profile 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 MHD regime. The 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 field has been investigated, culminating in the demonstration that this conditioning scheme allows to recover normal operation after disruptions. Effect of the magnetic field 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 to predictions by 5D gyrokinetic codes: numerical results simultaneously match the magnitude of effective heat diffusivity, rms values of density fluctuations, and wave-number 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 fluctuations has been studied by correlating data from fast imaging cameras and Langmuir probes, yielding a coherent picture of transport processes involved in the SOL.
Journal of Nuclear Materials, 2009
On the limiter of Tore Supra, the heat loads map computed from deconvolution of IR surface temper... more On the limiter of Tore Supra, the heat loads map computed from deconvolution of IR surface temperatures shows good agreement with calorimetry measurements. This experimental heat pattern allows deducing the heat fluxes in the scrape-off layer using a 3D magnetic calculation and assuming only parallel heat transport along field lines. This calculation leads to an underestimation of the power circulating in the edge plasma according to the power balance, similarly to RFA measurements. The comparison between experimental heat loads on the limiter and modelling also shows a spreading of heat fluxes near the LCFS that cannot be explained only by parallel transport in the SOL.
Journal of Nuclear Materials, 2009
This paper focuses on chemical erosion characterisation at Tore Supra by visible spectral analysi... more This paper focuses on chemical erosion characterisation at Tore Supra by visible spectral analysis of carbon and deuterium transitions at the toroidal pumped limiter-the main source of carbon. A new imageprocessing tool for visible imaging analysis allows to identify carbon sources on the limiter. Spectrally resolved data have been also obtained on the limiter in particular the observation of the CD band (Gerö band), related to chemical erosion. Erosion yields have been assessed and chemical erosion represents roughly 30% of the total carbon erosion.
IEEE Transactions on Plasma Science, 2011
ABSTRACT In fusion devices, infrared (IR) imaging systems are used routinely for monitoring the s... more ABSTRACT In fusion devices, infrared (IR) imaging systems are used routinely for monitoring the surface temperature of plasma-facing components exposed to high heat fluxes in order to prevent and assess potential damages. For a better understanding of the experimental IR measurements, a realistic photonic simulation has been developed from a ray-tracing Monte Carlo code. This simulation has been performed on the IR diagnostic of the existing fusion device Tore Supra in Cadarache (France). First IR simulated images are presented. The similar features of the light between the simulation and experimental data are then emphasized.
IEEE Transactions on Plasma Science, 2012
Diagnostics in ITER are supported by big structures called port plugs, the second main function o... more Diagnostics in ITER are supported by big structures called port plugs, the second main function of which is to ensure a sufficient shielding against neutrons and gammas. Regarding the integration of diagnostics in equatorial port plugs, a new approach is under study, which consists in installing the diagnostics in "drawers". This paper describes the recent work which has been performed in Europe on the integration of diagnostics in drawers in the Equatorial Port Plug 1 (EPPl). First the methodology which has been followed to progress on the integration of the diagnostics in this port plug is described and the resulting arrangement of diagnostics is shown. Then a special attention is paid to the integration of the two main diagnostics of EPPl, namely the visible/infrared wide angle viewing system and the radial neutron camera. Finally the preliminary design of the drawers of EPPl, in particular the shielding modules around the diagnostics, is presented, and the preliminary results of the analyses performed to validate this design are provided.
IEEE Transactions on Plasma Science, 2012
In the majority of nuclear fusion experiments equipped with carbonaceous Plasmas Facing Component... more In the majority of nuclear fusion experiments equipped with carbonaceous Plasmas Facing Components (PFCs), infrared imaging diagnostics are routinely used for monitoring the surface temperature of the Plasma Facing Components exposed to high heat fluxes. However, future fusion machines, such as ITER, will be equipped with metallic PFCs. As a consequence, due to their low emissivity the evaluation of the
IEEE Transactions on Plasma Science, 2012
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Papers by Jean-Marcel Travère