Main results of the first experimental campaign in the stellarator W7-X

A summary of the first operational phase (OP1.1) at the stellarator W7-X is given. The operational setup of heating and diagnostics as well the results of experiments are briefly described. Plasma parameters and confinement are better than expected: Te > 8 keV and Ti > 2 keV at ne ≈ 3×1019 m-3 yielding β0 ≈ 2.5 %. The results for ECR heating with X2-mode as well the ECCD are in good agreement with the theory predictions. The heating scenario with the O2-mode alone was successfully first time performed. Stellarator specific regime of core “electron root” confinement was obtained

Main results of the first experimental campaign in the stellarator W7-X

A summary of the first operational phase (OP1.1) at the stellarator W7-X is given. The operational setup of heating and diagnostics as well the results of experiments are briefly described. Plasma parameters and confinement are better than expected: T(b)> 8 keV and T(i)> 2 keV at n(b)≈ 3×10¹⁹ m⁻³ yielding β0 ≈ 2.5 %. The results for ECR heating with X2-mode as well the ECCD are in good agreement with the theory predictions. The heating scenario with the O2-mode alone was successfully first time performed. Stellarator specific regime of core “electron root” confinement was obtained.Представлены итоги первой экспериментальной кампании (ОР1.1) на стеллараторе W7-X. Вкратце описана специфика эксперимента, методов нагрева и основных диагностик. Параметры плазмы и удержание, полученные в экспериментах, превысили ожидаемые: T(b)> 8 кэВ и T(i)> 2 кэВ при ≈ n(b)≈ 3×10¹⁹ m⁻³, что соответствует β0 ≈ 2.5 %. Результаты по ЭЦР-нагреву на Х2-моде, а также по токам увлечения согласуются с теорией. Впервые был успешно реализован сценарий нагрева на О2-моде. Был также получен специфический для стеллараторов режим "электронного корня" удержания.Представлені підсумки першої експериментальної кампанії (ОР1.1) на стелараторі W7-X. Коротко описана специфіка експерименту, методів нагріву та діагностики. Параметри плазми та удержання, отримані в експериментах, перевищили очікувані: T(b)> 8 кеВ та T(i)> 2 > 2 кеВ при ≈ n(b)≈ 3×10¹⁹ m⁻³, що відповідає β0 ≈ 2.5 %. Результати по ЕЦР-нагріву на Х2-моді, а також по струмам захоплення відповідають теорії. Вперше був успішно реалізований сценарій нагріву на О2-моді. Був також успішно реалізований специфічний для стелараторів режим "електронного кореня" утримання

Experimental confirmation of efficient island divertor operation and successful neoclassical transport optimization in Wendelstein 7-X

We present recent highlights from the most recent operation phases of Wendelstein 7-X, the most advanced stellarator in the world. Stable detachment with good particle exhaust, low impurity content, and energy confinement times exceeding 100 ms, have been maintained for tens of seconds. Pellet fueling allows for plasma phases with reduced ion-temperature-gradient turbulence, and during such phases, the overall confinement is so good (energy confinement times often exceeding 200 ms) that the attained density and temperature profiles would not have been possible in less optimized devices, since they would have had neoclassical transport losses exceeding the heating applied in W7-X. This provides proof that the reduction of neoclassical transport through magnetic field optimization is successful. W7-X plasmas generally show good impurity screening and high plasma purity, but there is evidence of longer impurity confinement times during turbulence-suppressed phases.EC/H2020/633053/EU/Implementation of activities described in the Roadmap to Fusion during Horizon 2020 through a Joint programme of the members of the EUROfusion consortium/ EUROfusio

Modeling of W7-X superconducting coil cool-down using the 4C code

The recently developed 4C thermal-hydraulic code is validated here against experimental data from the cool-down of a non-planar coil of the Wendelstein 7-X stellarator from room temperature to the superconducting transition temperature of ∼10 K, performed during the cold test of the full set of coils at the cryomagnetic test facility of CEA Saclay. The computed results, i.e., temperature and mass flow rate evolutions in different coil components (helium, casing, etc.) are shown to be in good agreement with the experimental data. The simulations also show that during the transient the hot spot temperature inside the coil can be up to ∼3-4K higher than what is seen on the casing surfac

Amélioration des capacités antioxydantes de souches de bactéries lactiques (applications industrielles et thérapeutiques)

Les Bactéries Lactiques (BL), largement utilisées dans l'industrie pour la fabrication des produits laitiers fermentés, sont exposées au stress oxydant ce qui conduit à des pertes de rendement et diminue leur survie. De même, chez l'Homme, la formation d'espèces oxygénées réactives (ROS) par les phagocytes peut conduire dans le cas d'une inflammation anormale à un stress oxydant et à une perte de l'homéostasie intestinale. Le premier objectif de ce travail était l'obtention de souches de BL aux capacités antioxydantes améliorées et l'étude de leur physiologie lors d'un stress oxydant. Deux stratégies ont été développées. i) Des mutants spontanés de Lactococcus lactis résistant au stress oxydant (SpOx) et utilisables en industrie ont été obtenus. Les modifications moléculaires provoquées par la mutagenèse ont été identifiées par analyse protéomique. ii) Une catalase a été introduite par ingénierie génétique chez des souches de BL ce qui a permis d'éliminer H2O2, augmentant la survie lors d'un stress oxydant. Le deuxième objectif était d'évaluer les effets d'une BL antioxydante dans la prévention et le traitement de pathologies intestinales liées à la formation de ROS. Les effets de l'administration de Lb. casei produisant ou non MnKat ont été caractérisés dans un modèle murin d'inflammation intestinale. Indépendamment de la production de MnKat, Lb. casei limite les signes inflammatoires coliques. Ces résultats confirment l'intérêt de l'utilisation de Lb. casei pour traiter des pathologies inflammatoires intestinales. L'identification des mécanismes responsables de ces effets anti-inflammatoires pourrait permettre une meilleure compréhension des effets des probiotiques.Lactic acid bacteria (LAB), widely used for the production of fermented dairy products, are often exposed to oxidative stress leading to the decreases of production rates and of LAB survival. In human, the production of ROS by immune cells can led to oxidative stress and to a loss of intestinal homeostasis in the case of abnormal inflammation. The first aim of this work was to obtain LAB strains with improved antioxidative capacities and to study their behaviour during oxidative stress. We developed two strategies: i) Spontaneous Oxidative stress resistant mutants (SpOx) of Lactococcus lactis were obtained using natural selection. The molecular modifications induced by the mutagenesis were identified using a comparative proteomic analysis. ii) A catalase was introduced in LAB strains which are to eliminate H2O2 and have an improved survival when exposed to oxidative stress. The second aim of this work was to evaluate preventive or therapeutic effects of an antioxidative LAB strain in the case of intestinal disorders related to oxidative stress. The effects of Lb. casei, producing or not MnKat, administration were characterized using an intestinal colitis model in mice. Independently to the presence of MnKat, Lb. casei administration reduces inflammatory scores of colonic mucosa. Identification of the mechanisms leading to anti-inflammatory properties of Lb. casei BL23 could help to better understand the probiotics effects. These results confirm the high interest of Lb. casei utilisation for the treatment of intestinal inflammatory diseases.ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF