43 research outputs found

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

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    Towards a new image processing system at Wendelstein 7-X: From spatial calibration to characterization of thermal events

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    Wendelstein 7-X (W7-X) is the most advanced fusion experiment in the stellarator line and is aimed at proving that the stellarator concept is suitable for a fusion reactor. One of the most important issues for fusion reactors is the monitoring of plasma facing components when exposed to very high heat loads, through the use of visible and infrared (IR) cameras. In this paper, a new image processing system for the analysis of the strike lines on the inboard limiters from the first W7-X experimental campaign is presented. This system builds a model of the IR cameras through the use of spatial calibration techniques, helping to characterize the strike lines by using the information given by real spatial coordinates of each pixel. The characterization of the strike lines is made in terms of position, size, and shape, after projecting the camera image in a 2D grid which tries to preserve the curvilinear surface distances between points. The description of the strike-line shape is made by means of the Fourier Descriptors

    Forward modeling of collective Thomson scattering for Wendelstein 7-X plasmas: Electrostatic approximation

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    In this paper, we present a method for numerical computation of collective Thomson scattering (CTS). We developed a forward model, eCTS, in the electrostatic approximation and benchmarked it against a full electromagnetic model. Differences between the electrostatic and the electromagnetic models are discussed. The sensitivity of the results to the ion temperature and the plasma composition is demonstrated. We integrated the model into the Bayesian data analysis framework Minerva and used it for the analysis of noisy synthetic data sets produced by a full electromagnetic model. It is shown that eCTS can be used for the inference of the bulk ion temperature. The model has been used to infer the bulk ion temperature from the first CTS measurements on Wendelstein 7-X

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

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    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

    Paracodin zur Behandlung der Hemikranie

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    Die mikroanalytische Verwendung des „Thionalids“

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    Physical Symptoms, Distress, and Functional Disability in Youth With Chronic Orthostatic Intolerance

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    Objective: Youth with chronic orthostatic intolerance (OI) can experience significant physical, social, and academic functional debilitation. Previous studies have indicated associations among symptom severity, psychosocial factors, and functional disability. However, empirically tested models explaining how different medical and psychosocial factors may contribute to functional disability are lacking. The current cross-sectional study aimed to evaluate mediation, moderation, and additive models of the effect of physical symptoms and psychological distress on functional disability. Methods: One hundred and sixty-five youth (13-22 years old) undergoing medical evaluation of chronic OI symptoms completed measures of autonomic dysfunction symptom severity, depressive and anxiety symptoms, and functional disability. Models were evaluated using tests of indirect effects and linear and logistic regression analyses. Results: Results supported the mediation and additive effects models for depressive symptoms. Mediation, moderation, and additive models for hypothesized effects of anxiety symptoms were not supported. Conclusions: Results provide preliminary support for models in which OI symptoms affect functional debility via their effects on mood and in which depressive symptoms have unique and additive effects on functioning. Findings lay the foundation for longitudinal and experimental evaluation of biopsychosocial models of functional disability in youth with chronic OI and related conditions. Implications include the importance of a biopsychosocial conceptualization of OI symptoms and debility as a complex interplay of factors rather than as a purely physiological or psychological process
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