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Surface impedance characterization of high-temperature superconducting coated conductors for potential application in the future circular collider beam screen
Get PDF(English) The Future Circular Hadron Collider (FCC-hh) is a proposed hadron-hadron collider, with a center-of-mass collision energy of 100 TeV in an approximately 100-km long circular tunnel, aiming to push the frontiers of particle physics. One of the key elements in such a high-energy accelerator is the beam screen, which shields the cold superconducting magnets from the synchrotron radiation emitted by the proton beams at such high energies, ensures ultra-high vacuum conditions, and provides a low impedance to the circulating beams. Beam impedance depends on the electromagnetic interaction between the fields generated by the proton beam and the beam screen. In the current baseline design, the beam screen is made of 1 mm thick stainless steel plates coated with 0.3 mm of copper (Cu), but its surface impedance may not be low enough to guarantee a stable beam operation. The use of High-Temperature Superconductor (HTS) is thus being considered to improve the beam screen performance, particularly, those based on REBa2Cu3O7−x coated conductors (REBCO-CCs being RE = Y, Gd, Eu). It is therefore essential to estimate the surface impedance of these materials in the range of frequencies (2.1 kHz to 3 GHz), DC magnetic fields (1 to 16 T), and temperature (40-60 K) relevant for their use in the FCC-hh. The experimental characterization at the exact FCC-hh operating conditions is extremely challenging, and the surface impedance has to be inferred at conditions that are feasible with the current experimental capabilities.
In this thesis, we have addressed the full characterization of REBCO-CC as possible coatings for the beam screen. The first part presents a system of dielectric resonators to characterize the surface impedance of REBCO-CC materials at conditions as similar as possible to those foreseen in the FCC-hh. Results on representative REBCO-CC samples show the validity of the approach developed, providing surface impedance characterization up to 16 T, in a wide temperature range (4-100 K) and a frequency range between 6 and 15 GHz.
The second part evaluates the impact of using REBCO-CC to beam stability by performing calculations of the resistive wall beam impedance using a combination of finite integration techniques and beam coupling impedance theory for beam pipes of general cross-section. To this end, hybrid beam screen models combining REBCO-CC and Cu have been considered. The position of REBCO-CC and the percentage of coverage have been systematically studied to determine the optimum configuration that lowers the resistive wall impedance compared to that presented by Cu, while maintaining the magnetic field homogeneity seen by the beam within the specifications. We demonstrate in this study that it is possible to find a REBCO-CC coverage that improves the performance of the nominal beam screen.(Català) El Future Circular Hadron Collider (FCC-hh) és un col·lisionador d’hadrons proposat, amb una energia de col·lisió de centre de massa de 100 TeV en un túnel circular d’aproximadament 100 km de longitud, amb l’objectiu d’assolir nous límits en la física de partícules. Un dels elements clau en un accelerador d’alta energia com aquest és la pantalla de feix, que protegeix els imants superconductors freds de la radiació de sincrotró emesa pels feixos de protons a tan altes energies, assegura condicions de ultra alt buit i proporciona una baixa impedància als feixos de partícules circulants. La impedància del feix depèn de la interacció electromagnètica entre els camps generats pel feix de protons i la pantalla de feix. En el disseny de referència actual, la pantalla de feix està feta d’acer inoxidable de 1mm de gruix recobert amb 0.3 mm de coure (Cu), però la seva impedància superficial potser no és prou baixa per garantir una operació estable del feix. Per tant, s’està considerant l’ús de superconductors d’alta temperatura (HTS) per millorar el rendiment de la pantalla de feix, especialment aquells basats en conductors recoberts de REBa2Cu3O7−x (REBCO-CCs sent RE = Y, Gd, Eu). Per tant, és essencial estimar la impedància superficial d’aquests materials en el rang de freqüències (2.1 kHz a 3 GHz), camps magnètics de CC (1 a 16 T) i temperatura (40-60 K) rellevants per al seu ús en el FCC-hh. La caracterització experimental en les condicions de funcionament exactes del FCC-hh és extremadament complexa, i la impedància superficial ha d’inferir-se en condicions que siguin factibles amb les capacitats experimentals actuals. En aquesta tesi, hem abordat la caracterització completa de REBCO-CC com a possibles recobriments per a la pantalla de feix. La primera part presenta un sistema de ressonadors dielèctrics per caracteritzar la impedància superficial dels materials REBCO-CC en condicions el més semblants possibles a les previstes en el FCC-hh. Els resultats sobre mostres representatives de REBCO-CC mostren la validesa de l’enfocament desenvolupat, proporcionant una caracterització de la impedància superficial de fins a 16 T, en un ampli rang de temperatura (4-100 K) i un rang de freqüència entre 6 i 15 GHz. La segona part avalua l’impacte de l’ús de REBCO-CC en la estabilitat del feix realitzant càlculs de la impedància de paret resistiva del feix utilitzant una combinació de tècniques d’integració finita i teoria d’impedància de l’acoblament dels feixos per a tubs de feix de secció transversal general. Per a això, s’han considerat models de pantalla de feix híbrids que combinen REBCO-CC i Cu. La posició de REBCO-CC i el percentatge de cobertura s’han estudiat sistemàticament per determinar la configuració òptima que redueix la impedància de paret resistiva en comparació amb la presentada per Cu, mantenint al mateix temps la homogeneïtat del camp magnètic observat pel feix dins de les especificacions. Demostrem en aquest estudi que és possible trobar una cobertura de REBCO-CC que millori el rendiment de la pantalla de feix nominal.(Español) El Future Circular Hadron Collider (FCC-hh) es un colisionador de hadrones propuesto, con una energía de colisión de centro de masa de 100 TeV en un túnel circular de aproximadamente 100 km de longitud, con el objetivo de alcanzar nuevos límites en la física de partículas. Uno de los elementos clave en un acelerador de alta energía como éste es la pantalla de haz, que protege los imanes superconductores fríos de la radiación de sincrotrón emitida por los haces de protones a tan altas energías, asegura condiciones de ultra alto vacío y proporciona una baja impedancia a los haces de partículas circulantes. La impedancia del haz depende de la interacción electromagnética entre los campos generados por el haz de protones y la pantalla de haz. En el diseño de referencia actual, la pantalla de haz está hecha de acero inoxidable de 1 mm de espesor recubierto con 0.3 mm de cobre (Cu), pero su impedancia superficial puede no ser lo suficientemente baja para garantizar una operación estable del haz. Por lo tanto, se está considerando el uso de materiales superconductores de alta temperatura (HTS) para mejorar el rendimiento de la pantalla de haz, especialmente aquellas basadas en conductores recubiertos de REBa2Cu3O7−x (REBCO-CCs siendo RE = Y, Gd, Eu). Es esencial estimar la impedancia superficial de estos materiales en el rango de frecuencias (2.1 kHz a 3 GHz), campos magnéticos de CC (1 a 16 T) y temperatura (40-60 K) relevantes para su uso en el FCC-hh. La caracterización experimental en las condiciones de funcionamiento exactas del FCC-hh es extremadamente compleja, y la impedancia superficial debe inferirse en condiciones que sean factibles con las capacidades experimentales actuales. En esta tesis, hemos abordado la caracterización completa de REBCO-CC como posibles recubrimientos para la pantalla de haz. La primera parte presenta un sistema de resonadores dieléctricos para caracterizar la impedancia superficial de los materiales REBCO-CC en condiciones lo más similares posible a las previstas en el FCC-hh. Los resultados sobre muestras representativas de REBCO-CC muestran la validez del enfoque desarrollado, proporcionando una caracterización de la impedancia superficial de hasta 16 T, en un amplio rango de temperatura (4-100 K) y un rango de frecuencia entre 6 y 15 GHz. La segunda parte evalúa el impacto del uso de REBCO-CC en la estabilidad del haz realizando cálculos de la impedancia de pared resistiva del haz utilizando una combinación de técnicas de integración finita y teoría de impedancia de acoplamiento de haces para tubos de haz de sección transversal general. Para ello, se han considerado modelos de pantalla de haz híbridos que combinan REBCO-CC y Cu. La posición de REBCO-CC y el porcentaje de cobertura se han estudiado sistemáticamente para determinar la configuración óptima que reduce la impedancia de pared resistiva en comparación con la presentada por Cu, manteniendo al mismo tiempo la homogeneidad del campo magnético observado por el haz dentro de las especificaciones. Demostramos en este estudio que es posible encontrar una cobertura de REBCO-CC que mejore el rendimiento de la pantalla de haz nominal.DOCTORAT EN TEORIA DEL SENYAL I COMUNICACIONS (Pla 2013
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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