scholarly journals Hybrid simulation of NBI fast-ion losses due to the Alfvén eigenmode bursts in the Large Helical Device and the comparison with the fast-ion loss detector measurements

2020 ◽  
Vol 86 (5) ◽  
Author(s):  
R. Seki ◽  
Y. Todo ◽  
Y. Suzuki ◽  
K. Ogawa ◽  
M. Isobe ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Velocity Distribution ◽  
High Energy ◽  
The Other ◽  
Good Qualitative Agreement ◽  
Fast Ions ◽  
Magnetic Surfaces ◽  
Lorentz Equation ◽  
Hybrid Code ◽  
Fast Ion

The multiphase simulations are conducted with the kinetic-magnetohydrodynamics hybrid code MEGA to investigate the spatial and the velocity distributions of lost fast ions due to the Alfvén eigenmode (AE) bursts in the Large Helical Device plasmas. It is found that fast ions are lost along the divertor region with helical symmetry both before and during the AE burst except for the promptly lost particles. On the other hand, several peaks are present in the spatial distribution of lost fast ions along the divertor region. These peaks along the divertor region can be attributed to the deviation of the fast-ion orbits from the magnetic surfaces due to the grad-B and the curvature drifts. For comparison with the velocity distribution of lost fast ions measured by the fast-ion loss detector (FILD), the ‘numerical FILD’ which solves the Newton–Lorentz equation is constructed in the MEGA code. The velocity distribution of lost fast ions detected by the numerical FILD during AE burst is in good qualitative agreement with the experimental FILD measurements. During the AE burst, fast ions with high energy (100–180 keV) are detected by the numerical FILD, while co-going fast ions lost to the divertor region are the particles with energy lower than 50 keV.

PROBING AWAY SIDE JET MODIFICATION WITH THREE PARTICLE CORRELATIONS

2007 ◽  
Vol 16 (07n08) ◽  
pp. 1982-1987
Author(s):  
◽  
N. N. AJITANAND
Keyword(s):  
Spatial Distribution ◽  
Correlation Functions ◽  
Theoretical Models ◽  
The Other ◽  
Experimental Investigations ◽  
Powerful Method ◽  
Particle Correlation ◽  
Low Viscosity ◽  
Jet Modification ◽  
Rhic Data

Recent experimental investigations have focussed on the abnormal spatial distribution of away side jet fragments as signals of significant medium induced effects. A variety of theoretical models including recent string-theory based efforts have supported the notion of Mach Cone like effects in the low viscosity QGP fluid. However, the presence of significant flow fields may deflect the fragmentation direction producing a significantly differing type of jet topology from that of the Mach cone. Three particle correlation functions constitute a powerful method whereby the predominance of one or the other type of mechanism can be differentiated. In this work the use of such an approach will be demonstrated via simulations and the results of its application to RHIC data will be presented.

Computer studies of fast ion trajectories in crystals

1968 ◽  
Vol 46 (6) ◽  
pp. 503-516 ◽  
Author(s):  
D. V. Morgan ◽  
D. van Vliet
Keyword(s):  
Large Angle ◽  
Classical Dynamics ◽  
Perfect Lattice ◽  
Fast Ions ◽  
Angle Scattering ◽  
Initial Work ◽  
Fast Ion ◽  
Thermal Vibrations ◽  
Computer Studies ◽  
Good Agreement

A computer program has been developed which follows the trajectories of fast ions in crystals, based on the assumption of classical dynamics and binary collisions. Initial work has been directed at various aspects of proton channeling in copper in the energy range 5–500 keV. The critical angle and distance of closest approach in a perfect lattice have been evaluated for both rows and planes and compare well with the predictions of the continuum model as developed by Lindhard (1965). We also discuss the overlap of close-packed rows and planes, and the modifications necessary to the basic theory when thermal vibrations are introduced. Experiments have been simulated directly by obtaining a statistical analysis of the velocity distribution of protons reflected from a (100) face of copper and transmitted through a thin (~1800 Â) crystal. In reflection, distinct minima were obtained along directions corresponding to close-packed rows and planes, in good agreement with experimental "blocking patterns" (Nelson 1967a). Transmission patterns also revealed a lack of large-angle scattering parallel to close-packed planes, analogous to the white arms observed experimentally with thinner crystals.

Comparison of Stratification in a Water Tank and a PCM-Water Tank

2007 ◽  
Author(s):  
A. Castell ◽  
C. Sole´ ◽  
M. Medrano ◽  
M. Nogue´s ◽  
L. F. Cabeza
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Temperature Change ◽  
High Energy ◽  
Hot Water ◽  
The Other ◽  
High Energy Density ◽  
Water Tank ◽  
Charging And Discharging Processes ◽  
Change Material

Most of the storage systems available on the market use water as storage medium. Enhancing the storage performance is necessary to increase the performance of most systems. The stratification phenomenon is employed to improve the efficiency of storage tanks. Heat at an intermediate temperature, not high enough to heat up the top layer, can still be used to heat the lower, colder layers. There are a lot of parameters to study the stratification in a water tank such as the Mix Number and the Richardson Number among others. The idea studied here was to use these stratification parameters to compare two tanks with the same dimensions during charging and discharging processes. One of them is a traditional water tank and the other is a PCM-water (a water tank with a Phase Change Material). A PCM is good because it has high energy density if there is a small temperature change, since then the latent heat is much larger than the sensible heat. On the other hand, the temperature change in the top layer of a hot water store with stratification is usually small as it is held as close as possible at or above the temperature for usage. In the system studied the Phase Change Material is placed at the top of the tank, therefore the advantages of the stratification still remain. The aim of this work is to demonstrate that the use of PCM in the upper part of a water tank holds or improves the benefit of the stratification phenomenon.

Growth of Transition Metal Films on AL(110) Surfaces

1995 ◽  
Vol 399 ◽  
Author(s):  
R.J. Smith ◽  
Adli A. Saleh ◽  
V. Shutthanandan ◽  
N.R. Shivaparan ◽  
V. Krasemann
Keyword(s):  
High Energy ◽  
Metal Films ◽  
Surface Strain ◽  
The Other ◽  
Photoemission Spectroscopy ◽  
Alloy Formation ◽  
Ion Scattering ◽  
X Ray ◽  
Photoelectron Diffraction ◽  
Ti Films

ABSTRACTThe growth of thin Pd, Ni, Fe and Ti films on Al(110) surfaces has been studied using high-energy ion scattering (HEIS), x-ray photoemission spectroscopy and photoelectron diffraction techniques. Of these four metals, only Ti grows as an epitaxial overlayer, while the other metals mix with the substrate to form surface alloys. In the HEIS experiments the backscattered ion yield from Al surface atoms is measured as a function of metal coverage on the Al surface. A decrease in the Al scattering is observed for Ti deposition while the other metals result in increased Al scattering, attributed to alloy formation. An explanation for the exceptional growth behavior of Ti on Al is provided using a model of surface strain associated with aluminide formation.

A nanosecond pulse radiolysis study of the hydrated electron with high energy ions with a narrow velocity distribution

2004 ◽  
Vol 385 (1-2) ◽  
pp. 66-71 ◽  
Author(s):  
G. Baldacchino ◽  
G. Vigneron ◽  
J.-P. Renault ◽  
S. Pin ◽  
Z. Abedinzadeh ◽  
...  
Keyword(s):  
Velocity Distribution ◽  
Pulse Radiolysis ◽  
High Energy ◽  
Nanosecond Pulse ◽  
Hydrated Electron ◽  
High Energy Ions

scholarly journals Distribution of velocity and temperature between concentric rotating cylinders

1935 ◽  
Vol 151 (874) ◽  
pp. 494-512 ◽  
Keyword(s):  
Turbulent Flow ◽  
Velocity Distribution ◽  
The Other ◽  
Momentum Transport ◽  
Rotating Cylinders ◽  
Simultaneous Measurements ◽  
Other Hand ◽  
Vorticity Transport

It is not possible to distinguish between the Momentum Transport and the Vorticity Transport theories of turbulent flow by measurements of the distribution of velocity in a fluid flowing under pressure through pipes or between parallel planes. Only simultaneous measurements of temperature and velocity distribution are capable of distinguishing between the two theories in these cases. On the other hand, it will be seen later that measurements of the distribution of velocity between concentric rotating cylinders are capable of distinguishing between the two theories; in fact the predictions of the two theories in this case are sharply contrasted and mutually exclusive.

scholarly journals Hydrochemical Characteristics of the Surgut Reservoir Water Area Littoral Sections

2018 ◽  
Author(s):  
Keyword(s):  
Spatial Distribution ◽  
Power Plants ◽  
Thermal Power ◽  
Water Area ◽  
The Other ◽  
Anthropogenic Pressure ◽  
Taiga Zone ◽  
Thermal Power Plants ◽  
Reservoir Water ◽  
First Time

Cooling reservoirs of thermal power plants represent the special class of natural/ engineering systems with, on the one hand, natural geo/systems as one subsystem and, on the other hand, production/technological units as the other subsystem. Studying of these ecosystems’ functioning regularities seems to be helpful for water quality management and rational organization of water use. Besides, it is topical due to the low level of the relevant knowledge in the North of the Western Siberia. The authors for the first time in the Middle Ob Region have carried out a two-year session of monitoring of hydro/chemical indicators and temperature regime of the thermal power plants cooling reservoirs in the riparian stripe of water area. All previous investigations were done only by industrial water users within the frameworks of production monitoring in terms of three indicators in three points of the cooling reservoir water area downstream the power plant dam. Spatial distribution of concentrations of biogenic ions, salt composition, pH, organic matter, and metals in specific natural/technological system of the Surgut hthermal power plants’ reservoirs has been analyzed for the first time for the conditions of the Western Siberian taiga zone. Sources of anthropogenic pressure upon a water body have been identified. According the results of the indicators’ spatial distribution analysis three sections of the Surgut reservoir water area have been separated: a background section of the Chernaya River; a section upstream the dam with predominantly recreational character of the anthropogenic pressure; and a sectio0n downstream the dam with anthropogenic pressure of technological origin. According the outcomes of the correlation analysis indicators of the anthropogenic pressure character have been reveald.

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