7 research outputs found

    Herramienta de gestión de alertas categorizadas: MADALERT

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    El uso de aplicaciones en dispositivos móviles ha ido creciendo a lo largo de la última década a una velocidad vertiginosa, hasta llegar a convertirse hoy en día en una herramienta fundamental en la vida cotidiana de las personas. Este proyecto presenta un sistema formado por una aplicación para Android y una aplicación web que permite la gestión de alertas sobre sucesos que ocurren en tiempo real utilizando la geolocalización que ofrecen los dispositivos móviles. Las alertas que pueden seguirse pueden ser de alguna de las categorías definidas en el sistema. La aplicación está realizada para ser utilizada por cualquier tipo de usuario que quiera mantenerse al tanto de las alertas que puedan ocurrir en la ciudad de Madrid (España) y sus 21 distritos en los que está dividida

    Proyecto Puentes: conectando la universidad con la salud mental comunitaria

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    Se presenta la memoria del Proyecto Puentes, cuya finalidad es explorar e implementar vías de participación entre la comunidad universitaria y las personas con problemas de salud mental. Es decir, tender puentes entre lo académico y la realidad de esas personas, con el propósito de conseguir una fuente de aprendizaje significativo para el estudiantado de la UCM, pero también herramientas útiles en los procesos de recuperación e integración de las personas con problemáticas de salud mental.Depto. de Personalidad, Evaluación y Psicología ClínicaFac. de PsicologíaFALSEsubmitte

    A study of the physics of pellet injection in magnetically confined plasmas in stellarators

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    Mención Internacional en el título de doctorPlasma core fuelling is a key issue for the development of steady-state scenarios in large magnetically-confined fusion devices. This is of particular importance for helical-type machines, due to hollow density profiles predicted by neoclassical theory for on-axis microwave-heated plasmas. At present, cryogenic pellet injection is the most promising technique for efficient fuelling. However, further experimental and theoretical studies are necessary to fully understand all the mechanisms involved in pellet ablation and in the subsequent particle deposition, since a complete understanding of experimental results from non-axisymmetric devices remains outstanding. In this work, pellet ablation and fuelling efficiency experiments, using a pipe-gun type cryogenic pellet injector, are carried out in electron cyclotron resonance (ECRH) and neutral beam injection (NBI) heated hydrogen plasmas of the stellarator TJ-II. Here, all injections are made from the outer plasma side (inner plasma side injections are not possible for technical reasons). Ablation profiles are reconstructed from light emitted by the cloud that surrounds an ablating solid hydrogen pellet and collected by silicon photodiodes and a fast-frame camera system, under the assumptions that such emissions are loosely related to the ablation rate and that pellet radial acceleration in the plasma is negligible. Light emissions are also used to study the pellet penetration dependence on pellet and plasma parameters, such as pellet velocity, pellet mass, and plasma density for pellet injections from the outer plasma side of TJ-II. Pellet penetration in TJ-II, as in other magnetically confined plasma devices, increases with increasing pellet mass and velocity as well as for high plasma density and low temperature. However, if suprathermal electrons are present in the plasma core, they can limit pellet penetration due a sudden excess of ablation. In addition, pellet dynamics inside the plasma are analysed employing fast-camera images. Pellet radial acceleration is found to be zero or negligible. In addition, it is found that pellet injected into unbalance NBI-heated plasmas are deflected toroidally and poloidally. Furthermore, the drift direction and magnitude of the ionized fraction of the cloud, or plasmoid, is investigated using this fast-camera system. Plasmoids drifting, at between 0.5 and 20 km/s, towards the outer and lower plasma edge are observed. However, when pellets penetrate beyond the magnetic axis, plasmoids seem to drift towards the plasma centre. A dependence between plasmoid drift and plasmoid detachment position, related to rational surfaces, is observed. Also, pellet particle deposition profiles and fuelling efficiency are determined using pre- and post-injection density profiles provided by a Thomson Scattering (TS) system. Moreover, the influence of plasma heating methods on pellet ablation and material deposition is considered. Efficiency is found to depend significantly on pellet penetration depth. This is especially noted for NBI plasmas, since pellets penetrate beyond the plasma axis. In order to attain a deeper understanding of pellet injection physics in the TJ-II, experimental results are compared with theoretical predictions. In first instance, a neutral gas shielding-based code is adapted for TJ-II to compare experimental ablation rates for pellets injected into both ECRH and NBI-heated plasmas with simulated rates. Although penetration depths are well predicted by this model, ablation profiles only agree with experimental results for injections into ECRH plasmas. In addition, the Hydrogen Pellet Injection (HPI2) code, in its stellarator version, is used to simulate pellet injections into ECRH plasmas in TJ-II. With this code, using TS electron density and temperature profiles as input, ablation and material deposition predictions are compared with experimental measurements. Good agreement between experiment and simulations for pellet injections in TJ-II (ECRH) is obtained, except when suprathermal electrons are present in the plasma core. This agreement gives confidence in codes for stellarators, allowing predictions to be made with some sureness for the large W7-X device. The HPI2 code is then used to predict ablation and deposition profiles for pellets injected into relevant ECRH plasma scenarios in the stellarator W7-X, in particular corresponding to the second part of its initial operational phase, OP 1.2. Furthermore, comparisons with preliminary experimental results from OP 1.2 are presented. Predicted density profiles cannot reproduced experimental results, this being mainly attributed to the presence of suprathermal electrons. Finally, the HPI2 code is also used to simulate ablation and deposition profiles for pellets of different sizes and velocities injected into future relevant W7-X plasma scenarios, while estimating the plasmoid drift and the fuelling efficiency of injections made from two W7-X ports. These simulations allow identifying an advantageous port for efficient pellet injections into W7-X. The thesis presented here is divided into five chapters; of these, experimental and simulated results reported in Chapters 4 and 5 partially coincide with the main published contributions derived from this work [1–4].Programa Oficial de Doctorado en Plasmas y Fusión NuclearPresidente: Elena de la Luna Gargantilla.- Secretario: Luis Raúl Sánchez Fernández.- Vocal: Axel Loren

    Overview of first Wendelstein 7-X high-performance operation

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    The optimized superconducting stellarator device Wendelstein 7-X (with major radius , minor radius , and plasma volume) restarted operation after the assembly of a graphite heat shield and 10 inertially cooled island divertor modules. This paper reports on the results from the first high-performance plasma operation. Glow discharge conditioning and ECRH conditioning discharges in helium turned out to be important for density and edge radiation control. Plasma densities of with central electron temperatures were routinely achieved with hydrogen gas fueling, frequently terminated by a radiative collapse. In a first stage, plasma densities up to were reached with hydrogen pellet injection and helium gas fueling. Here, the ions are indirectly heated, and at a central density of a temperature of with was transiently accomplished, which corresponds to with a peak diamagnetic energy of and volume-averaged normalized plasma pressure . The routine access to high plasma densities was opened with boronization of the first wall. After boronization, the oxygen impurity content was reduced by a factor of 10, the carbon impurity content by a factor of 5. The reduced (edge) plasma radiation level gives routinely access to higher densities without radiation collapse, e.g. well above line integrated density and central temperatures at moderate ECRH power. Both X2 and O2 mode ECRH schemes were successfully applied. Core turbulence was measured with a phase contrast imaging diagnostic and suppression of turbulence during pellet injection was observed

    Major results from the first plasma campaign of the Wendelstein 7-X stellarator

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    After completing the main construction phase of Wendelstein 7-X (W7-X) and successfully commissioning the device, first plasma operation started at the end of 2015. Integral commissioning of plasma start-up and operation using electron cyclotron resonance heating (ECRH) and an extensive set of plasma diagnostics have been completed, allowing initial physics studies during the first operational campaign. Both in helium and hydrogen, plasma breakdown was easily achieved. Gaining experience with plasma vessel conditioning, discharge lengths could be extended gradually. Eventually, discharges lasted up to 6 s, reaching an injected energy of 4 MJ, which is twice the limit originally agreed for the limiter configuration employed during the first operational campaign. At power levels of 4 MW central electron densities reached 3 1019 m-3, central electron temperatures reached values of 7 keV and ion temperatures reached just above 2 keV. Important physics studies during this first operational phase include a first assessment of power balance and energy confinement, ECRH power deposition experiments, 2nd harmonic O-mode ECRH using multi-pass absorption, and current drive experiments using electron cyclotron current drive. As in many plasma discharges the electron temperature exceeds the ion temperature significantly, these plasmas are governed by core electron root confinement showing a strong positive electric field in the plasma centre.Peer reviewe

    Confirmation of the topology of the Wendelstein 7-X magnetic field to better than 1:100,000

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    Fusion energy research has in the past 40 years focused primarily on the tokamak concept, but recent advances in plasma theory and computational power have led to renewed interest in stellarators. The largest and most sophisticated stellarator in the world, Wendelstein 7-X (W7-X), has just started operation, with the aim to show that the earlier weaknesses of this concept have been addressed successfully, and that the intrinsic advantages of the concept persist, also at plasma parameters approaching those of a future fusion power plant. Here we show the first physics results, obtained before plasma operation: that the carefully tailored topology of nested magnetic surfaces needed for good confinement is realized, and that the measured deviations are smaller than one part in 100,000. This is a significant step forward in stellarator research, since it shows that the complicated and delicate magnetic topology can be created and verified with the required accuracy

    Major results from the first plasma campaign of the Wendelstein 7-X stellarator

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    \u3cp\u3eAfter completing the main construction phase of Wendelstein 7-X (W7-X) and successfully commissioning the device, first plasma operation started at the end of 2015. Integral commissioning of plasma start-up and operation using electron cyclotron resonance heating (ECRH) and an extensive set of plasma diagnostics have been completed, allowing initial physics studies during the first operational campaign. Both in helium and hydrogen, plasma breakdown was easily achieved. Gaining experience with plasma vessel conditioning, discharge lengths could be extended gradually. Eventually, discharges lasted up to 6 s, reaching an injected energy of 4 MJ, which is twice the limit originally agreed for the limiter configuration employed during the first operational campaign. At power levels of 4 MW central electron densities reached 3 10\u3csup\u3e19\u3c/sup\u3e m\u3csup\u3e-3\u3c/sup\u3e, central electron temperatures reached values of 7 keV and ion temperatures reached just above 2 keV. Important physics studies during this first operational phase include a first assessment of power balance and energy confinement, ECRH power deposition experiments, 2nd harmonic O-mode ECRH using multi-pass absorption, and current drive experiments using electron cyclotron current drive. As in many plasma discharges the electron temperature exceeds the ion temperature significantly, these plasmas are governed by core electron root confinement showing a strong positive electric field in the plasma centre.\u3c/p\u3
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