Rozprawy doktorskie na temat „Thermonuclear plasmas”
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Chaniotakis, E. A. (Emmanouil A. ). "Ignition and burn control characteristics of thermonuclear plasmas". Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/13659.
Pełny tekst źródłaIncludes bibliographical references (leaves 232-238).
by Emmanouil Antony Chaniotakis.
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1990.
BONANOMI, NICOLA. "Experimental investigation and gyro-kinetic modelling of turbulent transport in thermonuclear plasmas". Doctoral thesis, Università degli Studi di Milano-Bicocca, 2018. http://hdl.handle.net/10281/198976.
Pełny tekst źródłaITER (International Thermonuclear Experimental Reactor) will represent a fundamental step in the realization of controlled thermonuclear fusion. Among the problems still open, the understanding of the turbulent transport in the plasma is crucial for ITER, that will require high plasma temperature, density and confinement. This work focuses on four topics related to the thermal transport in a tokamak plasma core: the effects of light impurities, the effects of fast particles, the role of electron scale turbulence and multi-scale interactions and the effects of the plasma main ion mass (isotope effect). It covers the execution and analysis of experiments in JET tokamak L-mode plasmas, the use of local gyro-kinetic simulations (using the GENE code) to model the plasma and the test of the quasi-linear models TGLF and QuaLiKiz, used for ITER predictions. The turbulent transport in a tokamak is mainly due to instabilities on scales of the order of ion or electron Larmor radius driven by the ion and electron temperature gradients over a threshold in these gradients. Above the threshold, the turbulent flux increases with a rate that determines how stiff the temperature profiles are against an increase of heating power. Threshold and stiffness are key concepts used in this thesis to characterize the turbulent state of plasmas in different conditions. They are measured experimentally and compared to the theoretical predictions, providing a deeper insight into the plasma behavior and a stringent validation procedure for the models. Electron scale modes have been found determinant to explain the experimental electron heat flux and stiffness. A strong interaction between ion and electron scales was also found, with electron modes being strongest in conditions where ion scale modes are marginal stable, as will be the case in ITER. The TGLF model is in good agreement with the multi-scale gyro-kinetic simulations and can therefore be suitable for at least a qualitative exploration of these effects in future scenarios. Regarding the light impurities, the density profiles of 3He,Be,C,N and Ne show different peaking in the same plasmas, whilst theory predicts similar peaking for all the impurities. Discharges with N injection show higher peaking of Ti, well explained and reproduced by gyro-kinetic simulations. TGLF and QuaLiKiz show several discrepancies with the gyro-kinetic simulations. Indications have been provided on the improvements needed. A first experimental evidence of a strong thermal transport stabilization due to fast ions has been obtained in plasmas with low rotation. Gyro-kinetic simulations indicate two main stabilization mechanisms. One is electrostatic and related to a resonant wave-fast particle interaction, one is electromagnetic and sensitive to the total plasma pressure. The fast ion distribution function has also an influence on the level of the stabilization. These mechanisms are still not included in the quasilinear models. Finally, D plasmas have been compared to H plasmas with similar operational settings. Te and Ti are lower in H plasmas, the difference starting at the plasma edge. No substantial differences have been observed in the thermal transport in the plasma core at low power, but at high power, when fast ions are important, their stabilization effects appear less strong in H plasmas. An explanation has been found in the differences between the fast ion populations, with H plasmas featuring ~1/2 of the fast ion pressure in D, due to the different parameters of the heating systems. In conclusion, different aspects of thermal turbulent transport have been studied in JET L-mode plasmas. An interpretation of the experimental results has been reached with the help of gyro-kinetic simulations, and some physical effects have been evidenced to be relevant for future ITER scenarios. Some important indications on the validity and on possible improvements of the available numerical models have been obtained.
Auriemma, Fulvio. "Particle transport in Reversed Field Pinch plasmas". Doctoral thesis, Università degli studi di Padova, 2008. http://hdl.handle.net/11577/3425154.
Pełny tekst źródłaCommaux, Nicolas. "Contrôle du profil de densité dans le plasma de Tore Supra : comparaison de différentes méthodes d'alimentation en particules". Paris 11, 2007. http://www.theses.fr/2007PA112207.
Pełny tekst źródłaThe behaviour of a reactor-class plasma when fuelled using the existing techniques is difficult to foresee. The present work has been initiated on Tore Supra. Two topics have been studied: the comparison of the plasma behaviour when fuelled using the different techniques at high Greenwald density fractions and the study of the homogenisation following a pellet injection (fuelling technique for ITER burning plasmas). The experiments at high Greenwald density fractions performed on Tore Supra showed that the plasma behaviour is dependent on the fuelling method. The plasma energy confinement is following the scaling laws determined at low density when fuelled using pellet injection, which is better than for gas puffing and supersonic injection, both inducing a significant confinement loss. This behaviour is not related to transport but to the position of the matter source (at the edge for gas and close to the centre for pellets). The study concerning the homogenisation phenomena following a pellet injection aims to study the drift effect that expels the mater deposited toward the low field side. A new phenomenon was discovered: the influence of magnetic surfaces with an integer-valued safety factor (q). When the mater drifting toward low field side crosses an integer q surface, it experiences an effect that stops the drift motion. This study allows also determining that the drift following a pellet high field side injection appears negligible in Tore Supra. This work confirms that the pellet injection is an important tool for ITER plasma fuelling and that the low field side injection scheme should not be totally withdrawn for fuelling
Ballabio, Luigi. "Calculation and Measurement of the Neutron Emission Spectrum due to Thermonuclear and Higher-Order Reactions in Tokamak Plasmas". Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2003. http://publications.uu.se/theses/91-554-5512-3/.
Pełny tekst źródłaNOCENTE, MASSIMO. "Neutron and gamma-ray emission spectroscopy as fast ion diagnostics in fusion plasmas". Doctoral thesis, Università degli Studi di Milano-Bicocca, 2012. http://hdl.handle.net/10281/28397.
Pełny tekst źródłaFonseca, António Manuel Marques. "Alguns Aspectos do Desempenho do Tokamak TCABR: Modelamento, Simulações e Resultados Experimentais". Universidade de São Paulo, 2000. http://www.teses.usp.br/teses/disponiveis/43/43131/tde-30082006-121405/.
Pełny tekst źródłaIn this work, some aspects of the TCABR tokamak are studied. In particular, some points concerned to the plasma breakdown, to discharge characteristics in tokamak mode and to the vertical field system are investigated. A zero-dimensional model has been developed, especially for this work, based on five differential equations involving the ohmic heating circuit and the conservation laws of energy, electrical charge and neutral particles. The model was used for simulating the TCABR plasma discharges. Therefore, time profiles of important plasma parameters like plasma current, loop voltage, electron temperature, electron density and neutral density, were obtained. Also, as a result of the simulations, was verified how the tokamak machine parameters and plasma parameters influence the behavior of the discharges. Some experimental results from the TCABR and TCA were compared with the results of the simulations. A study of the rupture of the plasma was carried out adopting a physical model that includes many physical processes. This model was used to delimit the breakdown region for TCABR tokamak machine and as a tool to understand the experimental data. Experimentally, it was observed that, for TCABR, the rupture occurs for pressures values between 1.10-5 to 3.10-4 mbar, and electric fields values between 2 and 10 V/m. The ratio electric field-pressure (E/p), in the rupture region, is between 3.107 and 5.108 V.m-1.bar-1. For the control system of the vertical field we obtained some transfer functions mainly for the non-linear blocks of the system that have been used in the experimental tests. A computer program was developed to obtain the map of the magnetic vertical field lines and the index of curvature of the field. Finally it was verified that, in the center of the vessel, the ratio between the magnetic vertical field to the electric current that flows in the vertical coils is, 3.5.10-5 T/A and the index of curvature of the field is ~0.45.
Mukhtar, Qaisar. "On Monte Carlo Operators for Studying Collisional Relaxation in Toroidal Plasmas". Doctoral thesis, KTH, Fusionsplasmafysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-120590.
Pełny tekst źródłaQC 20130415
Monnier, Arnaud. "Interactions entre perturbations magnétiques macroscopiques et turbulence microscopique dans un modèle 3D d'un plasma de tokamak". Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4773/document.
Pełny tekst źródłaIn this thesis, the interaction between tokamak edge plasma and resonant magnetic perturbation (RMPs) is studied. It is mainly used to mitigate quasi-periodic relaxations in enhanced confinement regime. This regime allows to obtain good conditions for nuclear fusion. Introduction of a RMP in a tokamak plasma has been observed to modified the magnetic topology at the edge and decrease the relaxation amplitude up to complete suppression. Previous works studied the RMP effect on a plasma with relaxations, via numerical simulations. The model used for that consider the electrostatic approximation, where the magnetic topology does not evolve in time. In this thesis, the study is done with an edge plasma model taking into account magnetic fluctuations via the numerical code EMEDGE3D. This code has been modified to include the resonant magnetic perturbation. Comparison with reduced models has been carried out on the RMP penetration and the effect of sheared velocity on it. Then a RMP has been induced in a stable plasma, with or without imposed sheared rotation. A condition on the sheared velocity has been identified to avoid the screening effect, that would prevent the RMP penetration, analytically and in numerical simulations. This works has been repeated in a turbulent plasma in presence or not of transport barrier (sheared velocity). The turbulent plasma generate an effective RMP amplification, while the transport barrier is affected by locked convective cells due to the RMP
El, Messoudi Abdelmalek. "Modélisation des détonations thermonucléaires en plasmas stellaires dégénérés: applications aux supernovae de types Ia". Doctoral thesis, Universite Libre de Bruxelles, 2008. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210461.
Pełny tekst źródłaLes difficultés de modélisation des détonations proviennent essentiellement (i) de la libération d'énergie en plusieurs étapes, de l’apparition d’échelles de temps et de longueurs caractéristiques très différentes (ii) des inhomogénéités de densité, de température et de composition du milieu dans lequel se propage le front réactif et qui donnent naissance aux structures cellulaires et autres instabilités de propagation du front (extinctions et réamorçages locaux).
En plus de celles citées ci-dessus, deux autres difficultés majeures inhérentes à l'étude de ce mode de propagation dans les plasmas stellaires sont rencontrées :la complexité de l’équation d’état astrophysique et la cinétique nucléaire pouvant impliquer plusieurs milliers de nucléides couplés par plusieurs milliers de réactions. Ainsi, les premiers travaux impliquant une combustion thermonucléaire explosive ont été réalisés sur bases d'hypothèses simplificatrices comme l'équilibre nucléaire statistique instantané des produits de réactions ou l'utilisation d'un réseau réduit à une dizaine d'espèces nucléaires. Dans tous ces travaux, la détonation est assimilée à une discontinuité totalement réactive (détonation de Chapman-Jouguet ou CJ). La résolution de l'onde de détonation nécessite l'étude détaillée du processus nucléaire se déroulant dans la zone de réaction. Malheureusement, les supports de calculs actuels ne permettent pas encore ce type de simulations pour les détonations astrophysiques. Le modèle ZND qui constitue une description unidimensionnelle stationnaire de l’écoulement (plan ou courbé) constitue une excellente approximation de la réalité.
Notre travail réexamine les résultats des calculs des structures des ondes de détonations stellaires dans les conditions de température, de densité et de composition envisagées dans les travaux de ce type (détonation CJ et ZND) réalisés jusqu’à présent mais avec une équation d’état appropriée aux plasmas stellaires et une cinétique nucléaire nettement plus riche ;le plus grand réseau jamais utilisé pour ce genre d’études (333 noyaux couplés par 3262 réactions), prenant en compte les données les plus récentes de la physique nucléaire (vitesses de réaction et fonctions de partition)./Several astrophysics events like novae, supernovae and X burts, result from an explosive thermonuclear burning in stellar plasma. Type Ia Supernovae (SNeIa) count amoung the most fascinating stellar objects, they can be more brighter than an entire galaxy. Astrophysic works show that SNeIa may result from a thermonuclear explosion of a compact and dense star called carbon-oxygen white dwarf. The ignition stage and the propagation mode of the thermonuclear combustion wave are not identified yet. The Deflagration-to-Detonation Transition process (or "delayed detonation") sims to give the best overall agrements with the observations :detonations can play appart in SNeIa events.
Simulating thermonuclear detonations count same difficults. The most important are the burning length scales that spent over more than ten oders of magnitud, the nuclear kinetics that involve thousands of nuclids linked by thousands of nuclear reactions and the stellar plasma equation of state (EOS). Hydrodynamical simulations of detonation use very simplified ingedients like reduced reactions network and asymptotic EOS of completely electron degenerate stellar plasma.
Our work is the modelling of these detonations using more representative EOS of the stallar plasma that includs ions, electrons, radiation and electron-pistron pairs. We also use a more
detailed kinetic network, comprising 331 nuclids linked by 3262 capture and photodisintegration reactions, than those usualy employed.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
CASIRAGHI, IRENE. "First principle based integrated modelling in support of the Divertor Tokamak Test facility design". Doctoral thesis, Università degli Studi di Milano-Bicocca, 2023. https://hdl.handle.net/10281/402360.
Pełny tekst źródłaThe European research roadmap towards thermonuclear fusion energy defined eight different missions to guide the long–term programme. One of these crucial challenges is the controlled power and particle exhaust from a fusion reactor. To develop and test alternative strategies to solve the exhaust problem, in Italy a new experimental device is now under construction at the ENEA Research Center in Frascati: the Divertor Tokamak Test facility (DTT). Designing a new tokamak requires concerted efforts of physicists and engineers. To reduce costs and minimise risks, a first–principle based integrated modelling as comprehensive as possible of plasma discharges is an essential tool. The focus of this PhD project was to perform the first physics–based multi–channel simulations of the main baseline operational scenarios of DTT. In these simulations state–of–art modules for transport, heating, fuelling, and magnetic equilibrium are integrated to achieve self–consistent predictions of plasma profiles and scenario parameters. All non–linear interactions between heating and plasma and between the different transport channels are also calculated. During this work, the DTT simulations have been progressively enhanced adding codes to include a growing number of aspects and refining run settings. Moreover, updates of the heating systems, magnetic equilibria, and device configuration have been included to comply with the evolving machine design. The comparison among analogous simulations with different quasi–linear transport models made us confident in the reliability of the predicted plasma profiles and allowed us to identify the weak points of the models in the various DTT operational regimes. A validation of these quasi–linear models against the gyrokinetic simulations in the specific DTT range of parameters was also performed. The prediction accuracy has been improved recursively by matching the core and SOL simulation boundary conditions to guarantee the core–edge–SOL consistency. We investigated the full performance scenario to guide the machine design, and the first plasma and intermediate scenarios to assist the commissioning phases. The full performance scenario was tested with nine different heating mix options to select the optimal power distribution amongst the three auxiliary heating systems. The compatibility of the full power scenario with the electromagnetic coil system capabilities was then verified. In addition, the DTT sawteeth and ELMs during the full power scenario were estimated for the first time. An analysis of the required fuelling system performance to sustain the high density profiles proved that only the gas puffing system would be insufficient and that deuterium pellets are needed for the DTT fuelling. Neutron rates were evaluated and found compatible with the present design of the neutron shields. This PhD modelling work led to the optimisation of the device size and of the reference heating mix, and provided reference profiles for diagnostic system design, estimates of neutron yields, calculations of fast particle losses, gas puffing and/or pellet requirements for fuelling, MHD evaluations, and other tasks.
Fedorchenko, Ilya. "Thermonuclear engines in rocket science". Thesis, National Technical University of Ukraine "Igor Sikorsky Kyiv Polytechnic Institute", 2019. https://er.knutd.edu.ua/handle/123456789/15219.
Pełny tekst źródłaZornig, Nicolaas Hendricus. "Real time plasma control experiments using the JET auxiliary plasma heating systems as the actuator". Thesis, Brunel University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285095.
Pełny tekst źródłaMechhoud, Sarah. "Estimation de la diffusion thermique et du terme source du modèle de transport de la chaleur dans les plasmas de tokamaks". Phd thesis, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-00954183.
Pełny tekst źródłaCERECEDA, CARLO. "Ralentissement de particules chargees d'origine thermonucleaire dans un plasma magnetise". Paris 11, 1999. http://www.theses.fr/1999PA112065.
Pełny tekst źródłaPovilaitis, Mantas. "Plazmos sąveikos su pirmąja termobranduolinio reaktoriaus sienele modeliavimas". Master's thesis, Lithuanian Academic Libraries Network (LABT), 2008. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2008~D_20080627_091456-35082.
Pełny tekst źródłaIf a material is subjected to an ion flux, atomic composition of the material surface layer (first wall) can be modified by various plasma – first wall interaction processes. Therefore, a modified surface layer of the material is formed due to the plasma – first wall interaction. Effects of mixed materials can be a serious concern for the surface erosion. E.g., mixing of materials such as tungsten, carbon and beryllium in the fusion devices can influence important wall parameters such as a wall life time and hydrogen retention and permeation. Physical processes, which cause this modification, are not completely understood. A phenomenological model of plasma – first wall interaction is presented in the paper. Several possible simultaneous processes of plasma – first wall interaction are considered in the model: ion sputtering, adsorption of plasma particles on the surface, resorption of sputtered particles, thermal diffusion, implantation of plasma particles into the wall and cascade mixing. Selected chemical reaction is included in the model as well. Results of the simulation of low energy hydrogen plasma with 0.1% and 0.8% of carbon impurities interaction with tungsten surface are presented. Obtained results of the simulation are compared to the experimental results. Results of the calculation show importance of cascade mixing to the transport of carbon atoms in the target.
Pigatto, Leonardo. "Advanced Tools for Three-Dimensional Modeling and Control of Thermonuclear Fusion Devices". Doctoral thesis, Università degli studi di Padova, 2017. http://hdl.handle.net/11577/3422889.
Pełny tekst źródłaQuesta tesi rappresenta la raccolta delle attività svolte durante i tre anni di un progetto di Dottorato di Ricerca. Il lavoro è stato diviso principalmente in due parti, con il comune denominatore di investigare le problematiche relative alla stabilità e al controllo di instabilità Magneto-Idro-Dinamiche in plasmi di interesse fusionistico. Uno dei principali obiettivi di questo lavoro è lo studio di come questi plasmi interagiscano con diverse condizioni al contorno, strutturali ed elettro-magnetiche, con caratteristiche tridimensionali. Questa parte della ricerca è stata svolta sull'esperimento RFX-mod, dove è stato possibile sviluppare peculiari strategie di controllo grazie all'avanzato sistema di controllo attivo. Sono state affrontate varie problematiche tra loro interconnesse, a partire dallo sviluppo di tecniche per il miglioramento del contenuto armonico dei campi magnetici di vuoto tramite disaccoppiamento attuatori-sensori. Da ciò è stato sviluppato un metodo semplificato e applicabile in tempo reale per la compensazione di attuatori rotti o disattivati, con il medesimo obiettivo di migliorare il contenuto armonico dei campi magnetici prodotti dal sistema di controllo reale. A conclusione di questa parte il controllo multi-modale di modi di parete resistiva (RWM) è stato affrontato, dal punto di vista modellistico e sperimentale. Le strategie sviluppate e gli studi effettuati sono rilevanti sia per la configurazione Reversed Field Pinch sia per il Tokamak. Il primo è un ottimo terreno di prova per studiare i modi RWM, per via dello spettro di instabilità che naturalmente sviluppa. Per la seconda configurazione invece, la stabilizzazione dei modi RWM è considerato uno dei principali obiettivi da raggiungere sulla strada verso un reattore a fusione commerciale. La seconda parte del lavoro è relativa proprio alla problematica della stabilità RWM nella configurazione Tokamak, in particolar modo negli scenari avanzati in fase di sviluppo per l'esperimento JT-60SA. Una serie di studi è stata portata avanti con i codici MARS-F/K per determinare le proprietà dei modi RWM in plasmi ad alto beta, nei quali i profili di rotazione e le popolazioni di ioni sovra termici provenienti dagli iniettori di neutri possono giocare un ruolo importante. Da un lato una descrizione dettagliata del plasma, includendo gli effetti cinetici, è stata accoppiata a un modello semplificato e bidimensionale delle strutture passive. D'altra parte una più semplice descrizione del plasma è stata considerata per l'accoppiamento con un modello dettagliato e tridimensionale delle strutture attive e passive, in quest'ultimo caso è stato possibile sviluppare un modello di controllo attivo in catena chiusa dei modi RWM.
Bergkvist, Tommy. "Non-linear dynamics of Alfvén eigenmodes excited by fast ions in tokamaks". Doctoral thesis, KTH, Fusionsplasmafysik, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4320.
Pełny tekst źródłaQC 20100628
Mirza, Ahmed Akram. "Pressure driven instabilities in the reversed-field pinch : numerical and theoretical studies". Doctoral thesis, KTH, Fusionsplasmafysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-121345.
Pełny tekst źródłaQC 20130503
Banon, Navarro Alejandro. "Gyrokinetic large Eddy simulations". Doctoral thesis, Universite Libre de Bruxelles, 2012. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209592.
Pełny tekst źródłaDu point de vue théorique, la turbulence plasma est décrite par les équations gyrocinétiques, un ensemble d équations aux dérivées partielles non linéaires couplées. Par suite des très différentes échelles spatiales mises en jeu dans des conditions expérimentales réelles, une simulation numérique directe et complète (DNS) de la turbulence gyrocinétique est totalement hors de portée des plus puissants calculateurs actuels, de sorte que démontrer la faisabilité d’une alternative permettant de réduire l’effort numérique est primordiale. En particulier, les simulations de grandes échelles (”Large-Eddy Simulations” - LES) constituent un candidat pertinent pour permettre une telle r éduction. Les techniques LES ont initialement été développées pour les simulations de fluides turbulents à haut nombre de Reynolds. Dans ces simulations, les plus grandes échelles sont explicitement simulées numériquement, alors que l’influence des plus petites est prise en compte via un modèle implémenté dans le code.
Cette thèse présente les premiers développements de techniques LES dans le cadre des équations gyrocinétiques (GyroLES). La modélisation des plus petites échelles est basée sur des bilans d’énergie libre. En effet, l’energie libre joue un rôle important dans la théorie gyrocinétique car elle en est un invariant non lin éaire bien connu. Il est démontré que sa dynamique partage de nombreuses propriétés avec le transfert d’energie dans la turbulence fluide. En particulier, il est montré l’existence d’une cascade d énergie libre, fortement locale et dirigée des grandes échelles vers les petites, dans le plan perpendiculaire â celui du champ magnétique ambiant.
La technique GyroLES est aujourd’hui implantée dans le code GENE et a été testée avec succès pour les instabilités de gradient de température ionique (ITG), connues pour jouer un rôle crucial dans la micro-turbulence gyrocinétique. A l’aide des GyroLES, le spectre du flux de chaleur obtenu dans des simulations à très hautes résolutions est correctement reproduit, et ce avec un gain d’un facteur 20 en termes de coût numérique. Pour ces raisons, les simulations gyrocinétiques GyroLES sont potentiellement un excellent candidat pour réduire l’effort numérique des codes gyrocinétiques actuels.
/ Anomalous transport due to plasma micro-turbulence is known to play an important role in confinement properties of magnetically confined fusion plasma devices such as ITER. Indeed, plasma turbulence is strongly connected to the energy confinement time, a key issue in thermonuclear fusion research. Plasma turbulence is described by the gyrokinetic equations, a set of nonlinear partial differential equations. Due to the various scales characterizing the turbulent fluctuations in realistic experimental conditions, Direct Numerical Simulations (DNS) of gyrokinetic turbulence remain close to the computational limit of current supercomputers, so that any alternative is welcome to decrease the numerical effort. In particular, Large-Eddy Simulations (LES) are a good candidate for such a decrease. LES techniques have been devised for simulating turbulent fluids at high Reynolds number. In these simulations, the large scales are computed explicitly while the influence of the smallest scales is modeled.
In this thesis, we present for the first time the development of the LES for gyrokinetics (GyroLES). The modeling of the smallest scales is based on free energy diagnostics. Indeed, free energy plays an important role in gyrokinetic theory, since it is known to be a nonlinear invariant. It is shown that its dynamics share many properties with the energy transfer in fluid turbulence. In particular, one finds a (strongly) local, forward (from large to small scales) cascade of free energy in the plane perpendicular to the background magnetic field.
The GyroLES technique is implemented in the gyrokinetic code Gene and successfully tested for the ion temperature gradient instability (ITG), since ITG is suspected to play a crucial role in gyrokinetic micro-turbulence. Employing GyroLES, the heat flux spectra obtained from highly resolved direct numerical simulations are recovered. It is shown that the gain of GyroLES runs is 20 in terms of computational time. For this reason, Gyrokinetic Large Eddy Simulations can be considered a serious candidate to reduce the numerical cost of gyrokinetic simulations.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
Boucher, Dominique. "Etude et modelisation du transport de l'energie et des particules dans un plasma de fusion thermonucleaire controlee. Application au transport anormal et aux conditions de fonctionnement du tokamak". Palaiseau, Ecole polytechnique, 1992. http://www.theses.fr/1992EPXX0019.
Pełny tekst źródłaGeulin, Eléonore. "Contribution to the modeling of pellet injection : from the injector to ablation in the plasma". Electronic Thesis or Diss., Aix-Marseille, 2023. http://www.theses.fr/2023AIXM0066.
Pełny tekst źródłaThe preferred method of fueling fusion device is the use of D and/or T pellets injected into the plasma. They are currently used, but the results cannot be extrapolated to future larger reactors where the design of the injection system and the construction of scenarios will be mainly based on simulations. It is therefore important to fill in the gaps in the existing models from the manufacture of pellets to the deposition of material in the plasma. Two lacks of knowledge appear: the modeling of the pellet transport in the injection pipe and the validation of the ablation process. This work aims to fill these gaps and consists of 3 parts.- Describe the physics of material deposition, then the state of the art of the main results and finally the description of the pellet injection systems planned for the next machines.- Model the transport of the pellet in the injection pipe. The effects taken into account in the model are the weakening of the ice during rebounds, the increase in its temperature and its erosion. The model gives in particular the slowing down and the loss of mass of the pellet during the journey, as well as the stored elastic energy linked to its integrity on leaving the tube.- Contribute to the validation of the HPI2 ablation code, by comparing its predictions to data measured in ablation clouds. The method used is a calculation of synthetic data sets from simulations and comparing them to measurements. This method made it possible to validate the assumptions and approximations of the ablation model
Antl, Marek. "Napájecí soustava s pulsním generátorem pro tokamak COMPASS D". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2008. http://www.nusl.cz/ntk/nusl-217596.
Pełny tekst źródłaKlevarová, Veronika. "Materiály pro fúzní aplikace a jejich interakce s tokamakovým plazmatem". Master's thesis, 2016. http://www.nusl.cz/ntk/nusl-345466.
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