1,720,966 research outputs found
Noise-free rapid approach to solve kinetic equations for hot atoms in fusion plasmas
No full textAt the first wall of a fusion reactor, charged plasma particles are recombined into neutral molecules and atoms recycling back into the plasma volume where charge exchange (cx) with ions. As a result hot atoms with chaotically directed velocities are generated which can strike and erode the wall. An approach to solve the kinetic equation in integral form for cx atoms, being alternative to statistical Monte Carlo methods, has been speeded up by a factor of 50, by applying an approximate pass method to evaluate integrals, involving the ion velocity distribution function. It is applied to two-dimensional transfer of cx atoms near the entrance of a duct, guiding to the first mirror for optical observations. The energy spectrum of hot cx atoms, escaping into the duct, is calculated and the mirror erosion rate is assessed. Computations are done for a molybdenum first mirror under plasma conditions expected in the fusion reactor DEMO. Kinetic modeling results are compared with those found with a diffusion approximation valid in very cold and dense plasmas. For ducts at the torus outboard a more rigorous kinetic consideration predicts an erosion rate by a factor up to 2 larger than the diffusion approximation
Plasma Science and Technology
No full textUsually called the "fourth state of matter," plasmas make up more than 99% of known material. In usual terminology, this term generally refers to partially or totally ionized gas and covers a large number of topics with very different characteristics and behaviors. Over the last few decades, the physics and engineering of plasmas was experiencing a renewed interest, essentially born of a series of important applications such as thin-layer deposition, surface treatment, isotopic separation, integrated circuit etchings, medicine, etc. Plasma Science & Technology - Basic Fundamentals and Modern Applications presents the basic fundamentals behind plasma physics along with some of their most important modern applications
Spectroscopie photoassociative des états moléculaires faiblement liés du rubidium : <br />Analyse par la méthode de Lu-Fano.<br />Étude de la réalisation d'une lentille à atomes.
No full textThis thesis is composed of two parts. The first part presents the study of the realization of a lens for atoms using the dipolar interaction. A theoretical study suggests several possible experimental sequences allowing the realization of an achromatic lens with a controllable magnification. Attempts at realizing the sequence highlighted atom losses induced by the laser. The process of photoassociation, strongly probable under the experimental conditions, is responsible of these losses. The second part of this thesis reports on the recording of the photoassociation spectra. The analysis of the spectra obtained was carried out using the Lu-Fano graphs methods, which is often used in the physics of Rydberg atomic states. Applied to the three observed vibrational series, the method showed that the LeRoy-Bernstein formula, established to describe vibrational levels located in the asymptotic zone of the molecular potential, must be improved. The two suggested improvements consist in taking into account the short-range region of the potential well and the second term of the multipolar expansion. For a third series, the Lu-Fano graph exhibits a coupling between two vibrational series due to the spin-orbit and spin-spin interactions. The graph allowed a quantitative characterization of this coupling.Cette thèse se compose de deux parties. La première partie présente l'étude de la réalisation d'une lentille à atomes utilisant l'interaction dipolaire. Une étude théorique propose plusieurs séquences expérimentales possibles permettant la réalisation d'une lentille achromatique avec un grandissement contrôlable. Des tentatives de réalisation ont mis en évidence des pertes d'atomes induites par le laser utilisé. Le processus de photoassociation, fortement probable dans les conditions de l'expérience, est le responsable de ces pertes. La deuxième partie de cette thèse relate donc de l'enregistrement des spectres de photoassociation. L'analyse des spectres obtenus a été effectuée par la méthode des graphes de Lu-Fano, méthode souvent utilisée pour l'étude des séries de Rydberg. Appliqué aux trois séries vibrationnelles observées, la méthode a montré que la formule de LeRoy-Bernstein, établie pour décrire des niveaux vibrationnels situés dans la zone asymptotique du puits de potentiel moléculaire, doit être améliorée. Les deux améliorations proposées consistent à prendre en compte la région courte portée du puits de potentiel ainsi que le deuxième terme du développement multipolaire. Pour une troisième série, le graphe de Lu-Fano a mis en évidence un couplage dû à l'interaction spin-orbite et l'interaction spin-spin entre deux séries vibrationnelles. Le graphe a permis la caractérisation quantitative de ce couplage
Spectroscopie photoassociative des états moléculaires faiblement liés du rubidium : <br />Analyse par la méthode de Lu-Fano.<br />Étude de la réalisation d'une lentille à atomes.
No full textThis thesis is composed of two parts. The first part presents the study of the realization of a lens for atoms using the dipolar interaction. A theoretical study suggests several possible experimental sequences allowing the realization of an achromatic lens with a controllable magnification. Attempts at realizing the sequence highlighted atom losses induced by the laser. The process of photoassociation, strongly probable under the experimental conditions, is responsible of these losses. The second part of this thesis reports on the recording of the photoassociation spectra. The analysis of the spectra obtained was carried out using the Lu-Fano graphs methods, which is often used in the physics of Rydberg atomic states. Applied to the three observed vibrational series, the method showed that the LeRoy-Bernstein formula, established to describe vibrational levels located in the asymptotic zone of the molecular potential, must be improved. The two suggested improvements consist in taking into account the short-range region of the potential well and the second term of the multipolar expansion. For a third series, the Lu-Fano graph exhibits a coupling between two vibrational series due to the spin-orbit and spin-spin interactions. The graph allowed a quantitative characterization of this coupling.Cette thèse se compose de deux parties. La première partie présente l'étude de la réalisation d'une lentille à atomes utilisant l'interaction dipolaire. Une étude théorique propose plusieurs séquences expérimentales possibles permettant la réalisation d'une lentille achromatique avec un grandissement contrôlable. Des tentatives de réalisation ont mis en évidence des pertes d'atomes induites par le laser utilisé. Le processus de photoassociation, fortement probable dans les conditions de l'expérience, est le responsable de ces pertes. La deuxième partie de cette thèse relate donc de l'enregistrement des spectres de photoassociation. L'analyse des spectres obtenus a été effectuée par la méthode des graphes de Lu-Fano, méthode souvent utilisée pour l'étude des séries de Rydberg. Appliqué aux trois séries vibrationnelles observées, la méthode a montré que la formule de LeRoy-Bernstein, établie pour décrire des niveaux vibrationnels situés dans la zone asymptotique du puits de potentiel moléculaire, doit être améliorée. Les deux améliorations proposées consistent à prendre en compte la région courte portée du puits de potentiel ainsi que le deuxième terme du développement multipolaire. Pour une troisième série, le graphe de Lu-Fano a mis en évidence un couplage dû à l'interaction spin-orbite et l'interaction spin-spin entre deux séries vibrationnelles. Le graphe a permis la caractérisation quantitative de ce couplage
Spectroscopie photoassociative des états moléculaires faiblement liés du rubidium (analyse par la méthode de Lu-Fano)
No full textCette thèse se compose de deux parties. La première partie présente l étude de la réalisation d une lentille à atomes utilisant l interaction dipolaire. Une étude théorique propose plusieurs séquences expérimentales possibles permettant la réalisation d une lentille achromatique avec un grandissement contrôlable. Des tentatives de réalisation ont mis en évidence des pertes d atomes induites par le laser utilisé. Le processus de photoassociation, fortement probable dans les conditions de l expérience, est le responsable de ces pertes. La deuxième partie de cette thèse relate donc de l enregistrement des spectres de photoassociation. L analyse des spectres obtenus a été effectuée par la méthode des graphes de Lu-Fano, méthode souvent utilisée pour l étude des séries de Rydberg. Appliqué aux trois séries vibrationnelles observées, la méthode a montré que la formule de LeRoy-Bernstein, établie pour décrire des niveaux vibrationnels situés dans la zone asymptotique du puits de potentiel moléculaire, doit être améliorée. Les deux améliorations proposées consistent à prendre en compte la région courte portée du puits de potentiel ainsi que le deuxième terme du développement multipolaire. Pour une troisième série, le graphe de Lu-Fano a mis en évidence un couplage dû à l interaction spin-orbite et l interaction spin-spin entre deux séries vibrationnelles. Le graphe a permis la caractérisation quantitative de ce couplage.This thesis is composed of two parts. The first part presents the study of the realization of a lens for atoms using the dipolar interaction. A theoretical study suggests several possible experimental sequences allowing the realization of an achromatic lens with a controllable magnification. Attempts at realizing the sequence highlighted atom losses induced by the laser. The process of photoassociation, strongly probable under the experimental conditions, is responsible of the losses. The second part of this thesis reports on the recording of the photoassociation spectra. The analysis of the spectra obtained was carried out using the Lu-Fano graphs methods, which is often used in the physics of Rydberg atomic states. Applied to the three observed vibrational series, the method showed that the LeRoy-Bernstein formula established to describe vibrational levels located in the asymptotic zone of the molecular potential, must be improved. The two suggested improvements consist in taking into account the short-range region of the potential well and the second term of the multipolar expansion. For a third series, the Lu-Fano graph exhibits a coupling between two vibrational series due to the spin-orbit and spin-spin interactions. The graph allowed a quantitative characterization of this coupling.ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF
Cross Section Ionization By Electron Impact Of Helium Like Ions
Get PDFIn this paper we present our calculation of the cross section ionization by electron impact of C V, N VI and O VII. Using the Flexible Atomic Code (FAC), we obtain the cross sections for the ionization of these ions from the ground state 1The presentation of the authors' names and (or) special characters in the title of the pdf file of the accepted manuscript may differ slightly from what is displayed on the item page. The information in the pdf file of the accepted manuscript reflects the original submission by the author
Weakly bound 87 Rb 2 ( 5 s 1 / 2 + 5 p 1 / 2 ) 1 g molecules: Hyperfine interaction and LeRoy-Bernstein analysis including linear and nonlinear terms
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Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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