It is demonstrated that control software updates for the magnetic confinement fusion experiment EXTRAP T2R can enable novel studies of plasma physics. Specifically, it is shown that the boundary radial magnetic field in T2R can be maintained at finite levels by feedback. System identification methods to measure in situ magnetohydrodynamic stability are developed and applied with encouraging results. Subsequently, results from closed-loop identification are used for retooling the T2R regulator. The track of research here pursued could possibly be relevant for future thermonuclear fusion reactors. / QC 20100518

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The reversed-field pinch (RFP) is a magnetic confinement fusion (MCF) device. It exhibits a variety of unstable modes that can be explained by magnetohydrodynamic (MHD) theory. A particular unstable mode that is treated in this work is the resistive wall mode (RWM), which occurs when the shell of the device has finite conductivity. Application of control engineering tools appears to be important for the operation of the RFP. A model-based control approach is pursued to stabilize the RWM. The approach consists of experimental modeling of RWM using a class of system identification techniques. The obtained model is then used as a basis for Mode Predictive Control (MPC) design. The MPC employs the model to build predictions of the system and find a control input that optimizes the predicted behavior of the system. It is shown that the formulation of the MPC allows the user to incorporate several physics relevant phenomena aside from RWMs. The results are encouraging for MPC to be a useful tool for future MCF operation. / <p>QC 20150605</p>

Ground-based and in-situ observations of the aurora demonstrate an extreme richness in fine structure, with spatial scales down to tens of metres and time variations occurring on a fraction of a second. To further our understanding of the aurora, it is esssential to understand the mechanisms responsible for the small-scale structuring, since this is an intrinsic property of the auroral plasma. Still many questions about dynamics and structuring of aurora on small scales remain unanswered. In this thesis the low-light optical instrument ASK (Auroral Structure and Kinetics) is used to image small-scale structures in the aurora at very high spatial and temporal resolution. ASK is a multi-spectral instrument, imaging the aurora in three selected emission lines simultaneously. This provides information on the energy of the precipitating electrons. The SIF (Spectrographic Imaging Facility) instrument has been used in conjunction with ASK, to give a more complete picture of the spectral characteristics of the aurora, and to determine the contamination of the emission lines by other emissions. Data from ASK and SIF is used to study the relation between the morphology and dynamics of small-scale structures in the aurora and the energy of the precipitating electrons. By comparing electron density profiles provided by EISCAT (European Incoherent SCATter) measurements with modeling results, information on characteristic energy and energy flux of the precipitating electrons can be obtained. One of the ASK channels is imaging a metastable O+ emission, which has a lifetime of 5 s. By tracing the afterglow in this channel optically a direct measure of the E × B drift and thus of the local ionospheric electric fields is provided. / QC 20101109

An examination of the role of experiment in the cold fusion controversy is offered. It is argued that experimental results served as rhetorical tools in the service of actors in the controversy. Discourse analysis informed by actor network theory is employed to analyze the verbal and textual discourse of scientists involved in the construction of experimentally-based scientific knowledge. The practices actors employed to structure their discourse for rhetorical effectiveness are investigated. I conclude that if experiments are to retain their traditional role as arbiters of knowledge claims, the unit of analysis pertaining to "experiment" must be broadened to include not only experimental practices within the laboratory, but also the multitude of practices scientists perform outside the laboratory walls in order to increase the likelihood that their knowledge claims will be adopted by their disciplinary matrix. / Master of Science

Ce mémoire expose l’évolution de la régionalisation de services municipaux dans le Grand Sherbrooke entre 1990 et 2002 ainsi que les diverses solutions proposées pour gérer la panoplie d’ententes et de régies inter-municipales. Il cherche à établir si cette intégration des municipalités de la région au sein d’un ensemble métropolitain commun et de plus en plus centralisé a pu faciliter la fusion de 2002 ou non. Nous constaterons à ce sujet que la fusion aurait été évitable sans l’intervention du gouvernement du Québec. Par contre, une consolidation aurait eu lieu malgré tout, sous une forme ou une autre. La fusion a donc constitué une solution parmi tant d’autres, mais néanmoins celle que le gouvernement a choisi d’imposer aux régions métropolitaines du Québec. Les années 1990 marquent, dans la région de Sherbrooke, le début d’un processus de régionalisation de services comme l’eau potable, la police, les pompiers, la cour municipale, le transport en commun, etc. L’imposition de nouvelles normes ainsi que le délestage de responsabilités par le gouvernement provincial vers les municipalités ne sont pas étrangers à cette régionalisation. La conséquence de cela pour une région métropolitaine comme Sherbrooke est la multiplication d’ententes de services entre les municipalités de la région, principalement entre la ville-centre et une ou plusieurs villes de banlieue. À mesure que le phénomène progresse, des régies inter-municipales avec un véritable conseil d’administration sont créées dans le but de gérer ces services en commun. La multiplication de ces régies, combinée à la présence de la Municipalité régionale de comté (MRC), qui a ses pouvoirs propres, créent ainsi une sorte de palier de gouvernement non-officiel chapeautant toute la région et venant se superposer aux divers conseils municipaux. Plus une municipalité délègue la gestion de services à des régies ou à une MRC, moins elle a de contrôle direct sur ses propres actions.

<p>When the heavy hydrogen isotopes deuterium (D) and tritium (T) undergo nuclear fusion large amounts of energy are released. At the Joint European Torus (JET) research is performed on how to harvest this energy. Two of the most important fusion reactions, d+d→³He+n (E_n = 2.5 MeV) and d+t→⁴He+n (E_n = 14 MeV), produce neutrons. This thesis investigates how measurements of these neutrons can provide information on the fusion performance.</p><p>The Magnetic Proton Recoil (MPR) neutron spectrometer has operated at JET since 1996. The spectrometer was designed to provide measurements on the 14 MeV neutron emission in DT operation, thereby conveying information on the state of the fuel ions. However, a majority of today’s fusion experiments are performed with pure D fuel. Under such conditions, the measurements with the MPR were severely hampered due to interfering background. This prompted an upgrade of the instrument. The upgrade, described in this thesis, included a new focal plane detector, a phoswich scintillator array, and new data acquisition electronics, based on transient recorder cards. This combination allows for pulse shape discrimination techniques to be applied and a signal to background of 5/1 has been achieved in measurements of the 2.5-MeV neutrons in D experiments. The upgrade also includes a new control and monitoring system, which enables the monitoring and correction of gain variations in the spectrometer’s photo multiplier tubes. Such corrections are vital for obtaining good data quality.</p><p>In addition, this thesis describes a new method for determining the total neutron yield and hence the fusion power by using a MPR spectrometer in combination with a neutron emission profile monitor. The system has been operated at JET both during DT and D experiments. It is found that the systematic uncertainties are considerably lower (≈6 %) than for traditional systems. For a dedicated system designed for the next generation fusion experiments, i.e, ITER, uncertainties of 4 % could be attained.</p><p>Neutron spectroscopy can also be an important tool for determining the neutron emission from residual tritium in D plasmas. This information is combined with other measurements at JET in order to determine the confinement of the 1 MeV tritons from the d+d→t+p reactions.</p>

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No description available.