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Power exhaust and plasma divertor interaction study by means of a 2D edge numerical code
Get PDFLo scarico di un'elevata potenza ai target del divertore è considerato uno degli aspetti più critici verso il reattore distrativo (DEMO). DEMO è attualmente basato su una configurazione tokamak H-mode a singolo nullo. L'elevato flusso di particelle e potenza al divertore previsto per le macchine rilevanti a fini fusionistici può provocare la degradazione, la rottura e lo scieglimento dei componenti rivolti al plasma (PFC). Per questo motivo, configurazioni magnetiche alternative del divertore e l'uso di metalli liquidi come PFC sono attualmente studiati per testare l'affidabilità e la fattibilità dei futuri reattori.
Questa tesi di dottorato si concentra sullo studio dello Scrape-Off Layer (SOL) e del plasma del divertore su macchine da fusione esistenti e future per mezzo del codice numerico 2D SOLEDGE2D-EIRENE.
Il primo argomento presentato è lo studio della potenza scaricata negli esperimenti attuali. Per raggiungere questo obiettivo, le misure disponibili e i processi fisici inclusi o mancanti nel codice sono stati studiati per permettere una descrizione accurata degli esperimenti e per capire quali delle possibili discrepanze tra le simulazioni e le misure potrebbero essere attribuite a limitazioni del codice. Il secondo obiettivo principale era quello di prevedere i profili di trasporto e i coefficienti di interazione plasma-parete che potessero essere scalati ai futuri dispositivi di fusione.
I parametri di trasporto e di interazione plasma-parete derivati dalla modellizzazione dei presenti esperimenti sono stati la base per la modellizzazione predittiva degli scenari di plasma del Tokamak giapponese JT-60SA e della struttura Divertor Test Tokamak DTT. La modellizzazione degli scenari induttivi as alta potenza di ingresso di JT-60SA ha definito una gamma operativa in termini di potenza di ingresso, densità di plasma e concentrazione di impurezze per plasmi con o senza seeding di impurezze. Anche la modellazione di DTT mirava a definire un intervallo operativo con diverse impurezze che deve essere compatibile con le prestazioni del core. Lo studio dell'effetto della chiusura del divertore e della lunghezza di connessione sulla potenza scaricata, aveva lo scopo di analizzare i possibili vantaggi in termini di gestione della potenza che si potevano ottenere con queste geometrie. I risultati della modellazione degli scenari JT-60SA e DTT (plasma e densità neutra, temperatura e radiazione) sono stati utilizzati per testare le diagnostiche sintetiche come spettrometro e interferometro e sono stati utilizzati per testare gli effetti sul plasma dell'apertura ECRH durante il rump-up di DTT. Infine, un comportamento di tipo isteretico delle prestazioni di raffreddamento radiativo del plasma è stato osservato in entrambe le macchine, è stato descritto e giustificato teoricamente.
L'ultimo argomento presentato è lo studio dei metalli liquidi come esposta al plasma, concentrandosi sulla possibile implementazione per le operazioni DTT. A SOLEDGE2D-EIRENE è stato aggiunto un modulo autoconsistente per il calcolo del flusso di particelle emesse per sputtering e evaporazione. Il modulo, utlizzando l'energia in entrata e il flusso di particelle, stima la temperatura della superficie del metallo liquido tenendo conto di diverse configurazioni del target o metodi di raffreddamento. Il modulo stima in modo autoconsistente l'evaporazione delle particelle e lo sputtering e li usa come termini di sorgente in SOLEDGE2D-EIRENE. Quando il modello è stato applicato a DTT, si è trovato che il massimo flusso di potenza in ingresso per ottenere condizioni sostenibili al divertore potrebbe essere raddoppiato rispetto al caso senza sorgenti. La concentrazione di litio corrispondente nel plasma era accettabile, ma sono state studiate anche soluzioni alternative per abbassare la concentrazione di impurezze causata dall'alta potenza depositata ai target.The exhaust of a huge amount of power to the divertor targets is considered to be one of the most critical aspects towards the Demonstration power plant (DEMO). DEMO is presently based on a H-mode single null (SN) tokamak configuration. The elevated particle and power exhaust to the divertor targets foreseen in fusion-relevant machines can provoke degradation, cracking and even melting of the plasma-facing components (PFC). For this reasons, alternative magnetic divertor configurations (ADCs) and the use of liquid metal as PFC are currently studied to access the reliability and feasibility of future reactor machines.
This Ph.D. thesis focuses on the study of Scrape-Off Layer (SOL) and divertor plasma on existing and future fusion machines by means of the 2D-edge numerical code SOLEDGE2D-EIRENE.
The first topic presented is the study of power exhaust in current experiments by means of SOLEDGE2D-EIRENE. To achieve this goal, the available measurements and the physical processes included or missing in the code were investigated in order to allow an accurate description of the experiments and to understand which of the possible discrepancies between the simulations and the measurements could be attributed to limitations of the code. The second major aim was to predict transport profiles and plasma-wall interaction coefficients which could be scaled to future fusion devices.
Transport and plasma-wall interaction parameters derived from the modelling of present experiments were the basis for predictive modelling of plasma scenarios of the Japanese Tokamak JT-60SA and the Divertor Test Tokamak facility DTT. Modelling of JT-60SA inductive high input power scenarios defined an operative range in terms of input power, plasma density and impurity concentration for both seeded and unseeded plasmas. Modelling of DTT also aimed at defining an operative range with different seeded impurities which had to be compatible with core performances. The study of the effect on power exhaust of divertor closure and connection length aimed at analyzing the possible advantages in term of power handling that could be gained with these geometries. The outcome of the modelling of JT-60SA and DTT scenarios (plasma and neutral density, temperature an radiation) were used to test synthetic diagnostics like spectrometer and interferometer and were used to test the effects on the plasma of ECRH aperture during rump-up of DTT. Lastly, an hysteretical-like behaviour of cooling performances was observed in both machines, was described and theoretically justified.
The last topic presented is the study of liquid metal as plasma-facing components, focusing on the possible implementation for DTT operations. A self-consistent module for the evaluation of the sputtered and evaporated particles from the liquid metal was added to SOLEDGE2D-EIRENE. The module, reading the incoming energy and particle flux, estimates liquid metal surface temperature taking into account different target configurations or cooling methods. The module self-consistently estimate particle evaporation and sputtering and use them as sources in SOLEDGE2D-EIRENE. When the model was applied to DTT, it was found that the maximum input power flux to obtain sustainable conditions at the divertor could be doubled with respect to the unseeded case. The corresponding lithium concentration in the main plasma was acceptable, but alternative solutions were also studied to lower the impurity concentration caused by the high power and particle flux to the targets
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
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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