scholarly journals Локальные измерения флуктуаций радиальной скорости плазмы в токамаке ФТ-2 с помощью экваториального усиленного рассеяния

2020 ◽  
Vol 46 (15) ◽  
pp. 39
Author(s):  
А.Д. Гурченко ◽  
Е.З. Гусаков ◽  
А.Б. Алтухов ◽  
В.А. Иванов ◽  
А.В. Сидоров ◽  
...  
Keyword(s):  
Small Angle ◽  
Density Fluctuations ◽  
Plasma Velocity ◽  
Velocity Fluctuations ◽  
The Core ◽  
Microwave Beam ◽  
Hybrid Resonance ◽  
Angle Scattering ◽  
Core Plasma ◽  
Local Measurements

The possibility of local measurements of the level of the radial plasma velocity fluctuations by the equatorial enhanced scattering of a narrow microwave beam in the upper hybrid resonance in the core plasma of a tokamak is demonstrated. The limitations of the proposed method are clarified at the periphery of the plasma, where the amplitude of density fluctuations grows and small-angle scattering of microwaves on them along the path to the upper hybrid resonance and back becomes significant.

Local Measurements of Radial Plasma Velocity Fluctuations in the FT-2 Tokamak Using Equatorial Enhanced Scattering

2020 ◽  
Vol 46 (8) ◽  
pp. 767-770
Author(s):  
A. D. Gurchenko ◽  
E. Z. Gusakov ◽  
A. B. Altukhov ◽  
V. A. Ivanov ◽  
A. V. Sidorov ◽  
...  
Keyword(s):  
Plasma Velocity ◽  
Velocity Fluctuations ◽  
Local Measurements

scholarly journals The Core Subunit Structure in RNA Polymerase Holoenzyme Determined by Neutron Small-Angle Scattering

1980 ◽  
Vol 112 (2) ◽  
pp. 411-417 ◽  
Author(s):  
Peter STOCKEL ◽  
Roland MAY ◽  
Irmtraud STRELL ◽  
Zdenka CEJKA ◽  
Walter HOPPE ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Small Angle ◽  
Small Angle Scattering ◽  
Subunit Structure ◽  
The Core ◽  
Angle Scattering ◽  
Rna Polymerase Holoenzyme ◽  
Neutron Small Angle Scattering

Biological Small Angle Scattering

2018 ◽  
Author(s):  
Eaton E. Lattman ◽  
Thomas D. Grant ◽  
Edward H. Snell
Keyword(s):  
Small Angle ◽  
Density Fluctuations ◽  
General Interest ◽  
Comprehensive Treatment ◽  
Time Resolved ◽  
X Ray ◽  
Angle Scattering ◽  
Potential Applications ◽  
Electron Density Fluctuations ◽  
Contrast Matching

The technique of small angle solution scattering has been revolutionized in the last two decades. Exponential increases in computing power, parallel algorithm development, and the development of synchrotron, free-electron X-ray sources, and neutron sources, have combined to allow new classes of studies for biological specimens. These include time-resolved experiments in which functional motions of proteins are monitored on a picosecond timescale, and the first steps towards determining actual electron density fluctuations within particles. In addition, more traditional experiments involving the determination of size and shape, and contrast matching that isolate substructures such as nucleic acid, have become much more straightforward to carry out, and simultaneously require much less material. These new capabilities have sparked an upsurge of interest in solution scattering on the part of investigators in related disciplines. Thus, this book seeks to guide structural biologists to understand the basics of small angle solution scattering in both the X-ray and neutron case, to appreciate its strengths, and to be cognizant of its limitations. It is also directed at those who have a general interest in its potential. The book focuses on three areas: theory, practical aspects and applications, and the potential of developing areas. It is an introduction and guide to the field but not a comprehensive treatment of all the potential applications.

Influence of neglected small-angle scattering in radial distribution function analysis

1971 ◽  
Vol 4 (4) ◽  
pp. 277-283 ◽  
Author(s):  
G. S. Cargill
Keyword(s):  
Distribution Function ◽  
Radial Distribution Function ◽  
Radial Distribution ◽  
Small Angle ◽  
Function Analysis ◽  
Small Angle Scattering ◽  
Density Fluctuations ◽  
Atomic Density ◽  
X Ray ◽  
Angle Scattering

Materials containing inhomogeneities (density-fluctuations) of much greater than atomic size produce scattering at very small angles, which may go unobserved in many X-ray, electron, and neutron scattering experiments. For liquids and for amorphous and polycrystalline solids composed of one atomic species, an approximate expression for the reduced radial distribution function obtained from intensity measurements which neglect the small-angle scattering is shown to be Gexp(r) = 4πr{ρ(r) − ρ0[1 + (\overline {\eta^2}η2(ω)/ρ0 2)γ(ω, r)]} where ρ(r) is the atomic distribution function, ρ0 is the average atomic density, \overline {\eta^2}(ω) is the average square of atomic density fluctuations, γ(ω,r) is the density fluctuation correlation function, and ω is a volume element larger than the average atomic volume but smaller than the scale of long-range density fluctuations. This expression is also valid for systems composed of more than one type of atom where ρ(r) is a weighted average of pair distribution functions and [\overline {\eta^2}(ω)/ρ0 2]γ(ω,r) for X-ray scattering describes electron density fluctuations The neglect of small-angle scattering gives rise to a G exp(r) which appears, from its slope at small r, to correspond to a material of greater average atomic density ρ0,exp than that of the sample being studied. These results are illustrated by application to fluid argon (ρ0,exp/ρ0 = 1.17 near the critical point), to amorphous silicon (ρ0,exp/ρ0 = 1.13), and to phase separated PbO–B2O3 glasses (ρ0,exp/ρ0 = 1.07 for 24 wt. % PbO).

Concentration- and Density-Fluctuations with Amorphous Ni63Nb37 by Means of Neutron Scattering at Small Momentum Transfer (SANS)

1988 ◽  
Vol 43 (12) ◽  
pp. 1061-1064 ◽  
Author(s):  
M. Schaal ◽  
Ρ. Lamparter ◽  
S. Steeb
Keyword(s):  
Neutron Scattering ◽  
Momentum Transfer ◽  
Small Angle ◽  
Density Fluctuations ◽  
Small Momentum Transfer ◽  
Correlation Lengths ◽  
Small Momentum ◽  
Structure Factors ◽  
Angle Scattering ◽  
Constant Slope

By means of small angle neutron scattering SANS using isotopic substitution the medium range structure of the amorphous Ni63Nb37-alloy was investigated. From the coherently scattered intensi­ty in the region of small momentum transfer the total and partial Bhatia-Thornton structure factors were determined. For (Q-values down to 0.03 Å-1 no small angle scattering effect at all was observed. Compared to amorphous Ni80P20 this means that apparently no small regions exits in amorphous Ni63Nb37. For 0.008 Å-1 ≤ Q ≤ 0.03 Å-1, corresponding to correlation lengths between 800 and 200 A, however. Scc and SNN increase with almost constant slope of about 3.6 in the log S(Q) - logQ presentation.

Small Angle Electron Scattering From Vacuum Condensed Metallic Films

1968 ◽  
Vol 26 ◽  
pp. 380-381
Author(s):  
J. Silcox ◽  
R. H. Wade
Keyword(s):  
Electron Scattering ◽  
Small Angle ◽  
Ring Structure ◽  
Two Dimensional ◽  
Metallic Films ◽  
Micro Structure ◽  
Angle Scattering ◽  
The Fourier Transform ◽  
Source Of Information ◽  
Kinematical Theory

Recent work has drawn attention to the possibilities that small angle electron scattering offers as a source of information about the micro-structure of vacuum condensed films. In particular, this serves as a good detector of discontinuities within the films. A review of a kinematical theory describing the small angle scattering from a thin film composed of discrete particles packed close together will be presented. Such a model could be represented by a set of cylinders packed side by side in a two dimensional fluid-like array, the axis of the cylinders being normal to the film and the length of the cylinders becoming the thickness of the film. The Fourier transform of such an array can be regarded as a ring structure around the central beam in the plane of the film with the usual thickness transform in a direction normal to the film. The intensity profile across the ring structure is related to the radial distribution function of the spacing between cylinders.

Small angle scattering study of silica gels and zeolites

1993 ◽  
Vol 03 (C8) ◽  
pp. C8-393-C8-396
Author(s):  
T. P.M. BEELEN ◽  
W. H. DOKTER ◽  
H. F. VAN GARDEREN ◽  
R. A. VAN SANTEN ◽  
E. PANTOS
Keyword(s):  
Small Angle ◽  
Small Angle Scattering ◽  
Silica Gels ◽  
Angle Scattering ◽  
Scattering Study
Sign in / Sign up

Export Citation Format

Share Document