1,721,018 research outputs found
Production, acceleration and extraction of ions (negative/positive) from high-power laser induced plasma
No full textInternational audienceA novel scheme and methodology for the production, acceleration and extraction of ions, both negative and positive, for a broad spectrum of applications is investigated. The production of the plasma, from which the ions are extracted, is based on ultra-short high intensity laser beam interaction with clusters. The non-linear propagation and filamentation effects during the propagation of the ultra-short laser pulse in the clusters improve the volume ion production [1]. The selection of negative or positive ions extraction from the plasma is based on the magnetic insulation principle, where a strong external magnetic field is coupled to an accelerating electric field in a diode-like configuration [2]. The main advantages of the proposed ion source are (a) the high density of the produced ion beam and (b) the relatively small volume of production. A multi-fluid code in cylindrical geometry describes the spatio-temporal evolution of plasma species in the magnetically insulated diode configuration [3]. The code is also used to calculate the evolution of the state parameters of the plasma produced from filamentation [1]. These results enable us to investigate an improved configuration for plasma generation based on filamentation effects in (i) compact magnetic fusion devices and (ii) important applications of negative ion beams for plasma heating. The new high energy, high average power, high efficiency ICAN fiber laser [4] is a good candidate for both the plasma generation and the photoneutralization of negative ions beam. [1] Moustaizis, S. D., Auvray, P., Hora, H., Lalousis, P., Larour, J., and Mourou, G. "Photofusion reactions in a new compact device for ELI". In K. Osvay, P. Dombi, J. A. Fulop, and K. Varju (Eds.), AIP Conference Proceedings (Vol. 1462, No. 1, pp. 191-194), 2012. [2] Moustaizis, S. D., Lalousis, P., and Perrakis, K. "On the Production, Acceleration and Photo-Neutralization of High Energy and High Current Negative Ions Beam for Magnetic Fusion Applications". Paper contribution to the 39th EPS Conference and 16th Int. Congress on Plasma Physics, P1.026, Stockholm, 2012. [3] Moustaizis, S. D., Lalousis, P., Perrakis, K., Ducret, J. E., Larour, J., and Auvray, P. "Investigations on High Power Neutral Beam Production for Tokamak Applications.", Paper contribution to the 40th EPS Conference on Plasma Physics, P1.139, Espoo 2013. [4] Moustaizis, S. D., Lalousis, P., Perrakis, K., Auvray, P., Larour, J., Ducret, J. E., and Balcou, P. "ICAN: High power neutral beam generation". The European Physical Journal Special Topics, 224(13), 2639-2643, (2015)
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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
Lower hybrid current drive at high densities of ITER
No full textAs widely documented by available experimental and modelling data [1,2], a broadening
in the lower hybrid (LH) wave frequency and n_// (parallel wavenumber) spectrum is
produced by parametric instability (PI) that can affect the propagation and deposition of
the LH power launched in tokamak plasmas. The electronic dynamics at the plasma edge
mainly determines the occurrence of the ion-sound quasimode-driven PI, whose growth
rate is intrinsically high at the radial layers close to the antenna-plasma interface, as its
maximum occurs in the same conditions necessary for performing the antenna coupling
(i.e.: ω_pe⁄ω_0 ≥1 at the plasma edge). The radial extent in the plasma of the region with
high growth rate determines the spectral broadening size. Radially deeper is this region,
smaller are the convective losses and consequently bigger is the spectral broadening. The
present work shows that considering a case of relatively high densities (n_e) and low
electron temperatures (T_e) of the scrape-off layer (SOL), the LH spectral broadening
should be strong enough to produce the radiofrequency (RF) power deposition at the very
plasma periphery of ITER (International Thermonuclear Experiment Reactor).
Conversely, operating with slightly low ne and high T_e in the SOL, the radial extent of the
PI region results reduced and, consequently, a useful LHCD can be performed in the
plasma bulk
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