Correlation analysis for energy losses, waiting times and durations of type I edge-localized modes in the Joint European Torus

Several important ELM control techniques are in large part motivated by the empirically observed inverse relationship between average ELM energy loss and ELM frequency in a plasma. However, to ensure a reliable effect on the energy released by the ELMs, it is important that this relation is verified for individual ELM events. Therefore, in this work the relation between ELM energy loss (W-ELM) and waiting time (Delta t(ELM)) is investigated for individual ELMs in a set of ITER-like wall plasmas in JET. A comparison is made with the results from a set of carbon-wall and nitrogen-seeded ITER-like wall JET plasmas. It is found that the correlation between W-ELM and Delta t(ELM) for individual ELMs varies from strongly positive to zero. Furthermore, the effect of the extended collapse phase often accompanying ELMs from unseeded JET ILW plasmas and referred to as the slow transport event (STE) is studied on the distribution of ELM durations, and on the correlation between W-ELM and Delta t(ELM). A high correlation between W-ELM and Delta t(ELM), comparable to CW plasmas is only found in nitrogen-seeded ILW plasmas. Finally, a regression analysis is performed using plasma engineering parameters as predictors for determining the region of the plasma operational space with a high correlation between W-ELM and Delta t(ELM)

Study of recrystallization kinetics of stabilized ferritic stainless steels during hot rolling

Les aciers inoxydables ferritiques stabilisés, aussi performants dans de nombreux domaines et moins chers que les aciers inoxydables austénitiques, souffrent cependant d’une formabilité inférieure (mise en forme + défaut de chiffonnage / roping). Il convient donc d’optimiser les microstructures et textures finales de ces produits, ce qui passe entre autres par une meilleure connaissance de l’évolution du matériau durant le laminage à chaud (LAC).Des essais de bipoinçonnement effectués sur une machine Gleeble®, simulant la compression plane à cœur du matériau durant le LAC, ont permis de simuler des schémas de laminage mono et multipasses. Les effets de la déformation, de la température, de la vitesse de déformation, de la taille de grains initiale et de la composition chimique sur les évolutions dynamiques (durant une passe de laminage) et post-dynamiques (durant un temps interpasse) ont été investigués.Une passe de LAC fragmente la microstructure en cristallites par recristallisation dynamique continue (RDC). Une partie de ces cristallites deviendront les germes de la recristallisation post-dynamique (RPD) au cours du temps interpasse. Celui-ci se caractérise par la simultanéité d’activation de nouveaux germes, de la croissance de grains recristallisés au sein de zones écrouies mais également au détriment d’autres grains recristallisés.Le couplage d’un modèle de RDC existant avec un modèle de RPD créé à partir des observations expérimentales, permet de simuler des schémas de LAC multipasses et de retranscrire les effets de la majorité des paramètres opératoires.Stabilized ferritic stainless steels are as efficient as austenitic stainless steels in many areas and less expensive. However, they suffer from a lower formability (forming + roping defect). It is therefore necessary to optimize the final microstructures and textures of these products, which requires in particular a better understanding of the evolution of the material during hot rolling.Plane strain compression tests carried out on a Gleeble® machine, reproducing the deformation during hot rolling in the center of the material, permitted to perform single- and multi-pass rolling schedules. The effects of deformation, temperature, strain rate, initial grain size and chemical composition on dynamic (during a rolling pass) and post- dynamic (during an inter-pass time) evolutions were investigated.A hot rolling pass fragments the microstructure and creates crystallites by continuous dynamic recrystallization (CDRX). A part of these crystallites becomes nuclei for the post-dynamic recrystallization (PDRX) during inter-pass time. The latter is characterized by the simultaneous activation of new nuclei and growth of recrystallized grains, not only within strain-hardened zones but also at the expense of other grains already recrystallized.The coupling of an existing CDRX model with a PDRX model based on experimental results allows to simulate multi-pass hot rolling schedules and to reproduce the effects of most of the operating parameters

Etude de la cinétique de recristallisation au cours du laminage à chaud d’aciers inoxydables ferritiques stabilisés

Stabilized ferritic stainless steels are as efficient as austenitic stainless steels in many areas and less expensive. However, they suffer from a lower formability (forming + roping defect). It is therefore necessary to optimize the final microstructures and textures of these products, which requires in particular a better understanding of the evolution of the material during hot rolling.Plane strain compression tests carried out on a Gleeble® machine, reproducing the deformation during hot rolling in the center of the material, permitted to perform single- and multi-pass rolling schedules. The effects of deformation, temperature, strain rate, initial grain size and chemical composition on dynamic (during a rolling pass) and post- dynamic (during an inter-pass time) evolutions were investigated.A hot rolling pass fragments the microstructure and creates crystallites by continuous dynamic recrystallization (CDRX). A part of these crystallites becomes nuclei for the post-dynamic recrystallization (PDRX) during inter-pass time. The latter is characterized by the simultaneous activation of new nuclei and growth of recrystallized grains, not only within strain-hardened zones but also at the expense of other grains already recrystallized.The coupling of an existing CDRX model with a PDRX model based on experimental results allows to simulate multi-pass hot rolling schedules and to reproduce the effects of most of the operating parameters.Les aciers inoxydables ferritiques stabilisés, aussi performants dans de nombreux domaines et moins chers que les aciers inoxydables austénitiques, souffrent cependant d’une formabilité inférieure (mise en forme + défaut de chiffonnage / roping). Il convient donc d’optimiser les microstructures et textures finales de ces produits, ce qui passe entre autres par une meilleure connaissance de l’évolution du matériau durant le laminage à chaud (LAC).Des essais de bipoinçonnement effectués sur une machine Gleeble®, simulant la compression plane à cœur du matériau durant le LAC, ont permis de simuler des schémas de laminage mono et multipasses. Les effets de la déformation, de la température, de la vitesse de déformation, de la taille de grains initiale et de la composition chimique sur les évolutions dynamiques (durant une passe de laminage) et post-dynamiques (durant un temps interpasse) ont été investigués.Une passe de LAC fragmente la microstructure en cristallites par recristallisation dynamique continue (RDC). Une partie de ces cristallites deviendront les germes de la recristallisation post-dynamique (RPD) au cours du temps interpasse. Celui-ci se caractérise par la simultanéité d’activation de nouveaux germes, de la croissance de grains recristallisés au sein de zones écrouies mais également au détriment d’autres grains recristallisés.Le couplage d’un modèle de RDC existant avec un modèle de RPD créé à partir des observations expérimentales, permet de simuler des schémas de LAC multipasses et de retranscrire les effets de la majorité des paramètres opératoires

Comments on: "Is patient-specific instrumentation more precise than conventional techniques and navigation in achieving planned correction in high tibial osteotomy?" by N. Tardy, C. Steltzlen, N. Bouguennec, J.-L. Cartier, P. Mertl, C. Bataillé, et al. published in Orthop Traumatol Surg Res 2020;8S:S231-S236.

Place: FranceInternational audienc

Characterization of the CALIBAN Critical Assembly Neutron Spectra using Several Adjustment Methods Based on Activation Foils Measurement

CALIBAN is a metallic critical assembly managed by the Criticality, Neutron Science and Measurement Department located on the French CEA Center of Valduc. The reactor is extensively used for benchmark experiments dedicated to the evaluation of nuclear data, for electronic hardening or to study the effect of the neutrons on various materials. Therefore CALIBAN irradiation characteristics and especially its central cavity neutron spectrum have to be very accurately evaluated. In order to strengthen our knowledge of this spectrum, several adjustment methods based on activation foils measurements are being studied for a few years in the laboratory. Firstly two codes included in the UMG package have been tested and compared: MAXED and GRAVEL. More recently, the CALIBAN cavity spectrum has been studied using CALMAR, a new adjustment tool currently under development at the CEA Center of Cadarache. The article will discuss and compare the results and the quality of spectrum rebuilding obtained with the UMG codes and with the CALMAR software, from a set of activation measurements carried out in the CALIBAN irradiation cavity

Characterization of the CALIBAN Critical Assembly Neutron Spectra using Several Adjustment Methods Based on Activation Foils Measurement

CALIBAN is a metallic critical assembly managed by the Criticality, Neutron Science and Measurement Department located on the French CEA Center of Valduc. The reactor is extensively used for benchmark experiments dedicated to the evaluation of nuclear data, for electronic hardening or to study the effect of the neutrons on various materials. Therefore CALIBAN irradiation characteristics and especially its central cavity neutron spectrum have to be very accurately evaluated. In order to strengthen our knowledge of this spectrum, several adjustment methods based on activation foils measurements are being studied for a few years in the laboratory. Firstly two codes included in the UMG package have been tested and compared: MAXED and GRAVEL. More recently, the CALIBAN cavity spectrum has been studied using CALMAR, a new adjustment tool currently under development at the CEA Center of Cadarache. The article will discuss and compare the results and the quality of spectrum rebuilding obtained with the UMG codes and with the CALMAR software, from a set of activation measurements carried out in the CALIBAN irradiation cavity

Effect of sliding velocity on friction-induced microstructural evolution in Copper

International audienceDurability of engineering workpieces surfaces is well-known to be strongly related to the microstructural evolutions induced by machining processes. One current challenge is to choose the right process parameters, such as the sliding speed, in order to optimize both the subsurface microstructure and the surface properties. In this paper, a special tribometer, able to simulate contact pressures and cutting speeds occurring during machining, has been used to characterize the effect of sliding velocity on microstructural evolution induced in copper. Significant recrystallization and grain refinement phenomena have been observed for the highest sliding speed tested (250m/min). Finite element analysis have been performed to extract local variables near the pin/copper bar interface. A good agreement is noticed between the equivalent plastic strain level, the temperature rise, the resulting grain size and the hardness gradient

LOW AND INTERMEDIATE ENERGY HEAVY ION COLLISIONS IN THE SEMI-CLASSICAL MICROSCOPIC DESCRIPTION

Cette contribution est consacrée à la description des collisions centrales périphériques à l'aide d'une dynamique Landau-Vlasov. Pour les collisions périphériques aux énergies intermédiaires, les corrélations masse-masse, les énergies moyennes des quasi-projectiles et les distributions angulaires sont obtenues et comparés avec les données expérimentales. Pour les collisions centrales, on montre que la fenêtre de fusion de TDHF à basse énergie disparaît avec l'introduction d'une intéraction résiduelle. Au-delà de 20 MeV/u, la fusion incomplète est décrite avec le transfert d'impulsion et les déformations nucléaires associées. Le couplage aux états du continuum est analysé dans les dynamiques Vlasov et Landau-Vlasov. L'intéraction Coulombienne étant incorporée, nous présentons des résultats sur le transfert d'isospin et l'excitation du mode dipolaire isovectoriel au voisinage et au-dessus de la barrière Coulombienne. Quelques perspectives pour l'étude d'observables physiques sont finalement tracées.It is shown how peripheral and central heavy-ion collisions can be described by Landau-Vlasov dynamics. For peripheral collisions at intermediate energies, mass-mass correlations, ejectile mean energies and angular distributions are obtained and compared with fragmentation data. For central collisions, one shows that the collision term destroys the TDHF property of transparency at low impact parameters for collisions close from the Coulomb barrier. Above 20 MeV/u incomplete fusion is described with associated linear momentum transfer and nuclear deformations. One exhibits how coupling to the continuum is obtained in Vlasov and Landau-Vlasov dynamics. Coulomb interaction being taken into account, we present also results concerning the isospin transfer and the excitation of the isovector dipole mode near and well above the Coulomb barrier. Some perspectives to further studies of physical observables are finally drawn