1,721,074 research outputs found
An electron gun for electron-cooling device
No full textAn electron gun specifically designed for high energy electron cooling is presented. The energy resolution of such a device is <8.3*10-6
Analytical calculation of space charge current of high-voltage plane diode electron gun
No full textThe standard paraxial-ray equation method for calculation of space charge current is included the effect of the beam's azimuthal magnetic field. Analytical expression for plane diode is obtained and is expected to be a more precise solution for high-voltage electron gun
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
Proposal for a deflecting system for streak camera with sub-ps resolution and wide dynamic range
No full textWe propose an idea of a new scheme for significant improvement in streak cameratechnology. With the use of a radio-frequency-based spiral scanning sub-ps resolution can be maintained for an observation interval as long as 10 ns. In the new scheme, two operational regimes can be set for the camera. The first one is the circular scanning regime, which is suitable for single-light pulses with a total duration less than one RF period. The second regime accomplishes a spiral scanning, i.e., a circular scanning with variable strength, to overcome the problem of small duration of RF period. This regime is provided by an appropriate decrease in amplitude for the RF field in the cavities of the camera. A spiral scanning technique can be realized by the fast RF energy transition between two coupled cavities driven by a microwave switch
Design of the beam line and energy recovery system for a high-energy electron cooling device
No full textThe design of the beam line for a high-energy electron cooling device is presented. In order to avoid an electron dump of the order of few MW and to save the installed power, an efficient energy recovery system has been designed. The computer simulations of the electron gun and collecting device are discusse
MONTE-CARLO SIMULATION OF A GAAS ELECTRON SOURCE
No full textPhotoelectron transport in a GaAs electron source was studied using a Monte Carlo simulation technique. The principle of the method is to simulate the motion of photoexcited hot electrons in GaAs real space, taking into account various scattering mechanisms. The calculated electron energy distribution is in very good agreement with experimental measurements. The calculation predicts the electron emittance at the GaAs surface being from 2.70 pi to 3.29 pi mm mrad and the electron transit time spread (TTS) of the source ranging from 270 to 284 ps. It was also found that the hot photoelectron mean free path is 117.5 to 39.4 nm with the incident photon energy changing from 1.6 to 2.5 e
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
CALCULATED SPIN POLARIZATION OF FIELD-ASSISTED GAAS ELECTRON SOURCE
No full textCalculations are reported showing that for the field-assisted GaAs NEA photocathode, the spin polarization of emitted electrons can be 3.6 times higher than for non-field GaAs sources. The reason for this is that the electron diffusion time in field-assisted GaAs cathodes is shorter than that in conventional GaAs NEA cathodes
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