scholarly journals Распыление вольфрама ионами бериллия и неона

2020 ◽  
Vol 46 (24) ◽  
pp. 19
Author(s):  
Д.С. Мелузова ◽  
П.Ю. Бабенко ◽  
А.Н. Зиновьев ◽  
А.П. Шергин
Keyword(s):  
Experimental Data ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Ion Bombardment ◽  
Dynamics Simulation ◽  
Tokamak Plasma ◽  
Universal Behavior ◽  
Sputtering Yields ◽  
Good Agreement ◽  
Near Threshold

Sputtering yields for tungsten under Be and Ne ion bombardment as well as angular dependencies of the sputtering yields were calculated using molecular dynamics simulation. The results for Ne are in good agreement with experimental data. The obtained results for Be-W sputtering are needed to calculate the impurity influx into the plasma when the divertor material - tungsten - is bombarded with Be ions in ITER tokamak plasma. A model that explains the universal behavior of near-threshold sputtering yields for light ion-induced sputtering of tungsten was proposed.

GRANULAR MEDIA ON A VIBRATING PLATE: A MOLECULAR DYNAMICS SIMULATION

1993 ◽  
Vol 07 (09n10) ◽  
pp. 1779-1788 ◽  
Author(s):  
JASON A.C. GALLAS ◽  
HANS J. HERRMANN ◽  
STEFAN SOKOLOWSKI
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Granular Materials ◽  
Granular Medium ◽  
Granular Media ◽  
Dynamics Simulation ◽  
Dissipation Of Energy ◽  
Conveyor Belts ◽  
Good Agreement ◽  
Vibrating Plate

When sand or other granular materials are shaken, poured or sheared many intriguing phenomena can be observed. We will model the granular medium by a packing of elastic spheres and simulate it via Molecular Dynamics. Dissipation of energy and shear friction at collisions are included. The onset of fluidization can be determined and is in good agreement with experiments. On a vibrating plate we observe the formation of convection cells due to walls or amplitude modulations. Density and velocity profiles on conveyor belts are measured and the influence of an obstacle discussed. We mention various types of rheology for flow down an inclined chute or through a pipe and outflowing containers.

THE CORRELATION BETWEEN BOND ANGLE DISTRIBUTION AND THE COORDINATION OF SILICA LIQUID UNDER PRESSURE

2012 ◽  
Vol 26 (20) ◽  
pp. 1250117 ◽  
Author(s):  
L. T. VINH ◽  
N. V. HUY ◽  
P. K. HUNG
Keyword(s):  
Experimental Data ◽  
Molecular Dynamics ◽  
Bond Angle ◽  
Simple Expression ◽  
Dynamics Simulation ◽  
Angle Distribution ◽  
Bond Angle Distribution ◽  
Simulation Results ◽  
Substantial Change ◽  
Good Agreement

Molecular dynamics simulation is carried out for liquid SiO 2 at pressure ranged from zero to 30 GPa and by using BKS, Born–Mayer type and Morse–Stretch potentials. The constructed models reproduce well the experimental data in terms of mean coordination number, bond angle and pair radial distribution function. Furthermore, the density of all samples can be expressed by a linear function of fractions SiO x. It is found that the topology of units SiO x and linkages OSi y is unchanged upon compression although the liquid undergoes substantial change in its network structure. Consequently, the partial bond angle distribution for SiO x and OSi y is identical for all samples constructed by the same potential. This result allows to establishing a simple expression between total bond angle distribution (BAD) and fraction of SiO x and OSi y. The simulation shows a good agreement between the calculation and simulation results for both total O–Si–O and Si–O–Si BADs. This supports a technique to estimate amount of units SiO x and linkages OSi y on base of total Si–O–Si and O–Si–O BADs measured experimentally.

Thermal Conductivity of Individual Single-Wall Carbon Nanotubes

2006 ◽  
Vol 129 (6) ◽  
pp. 705-716 ◽  
Author(s):  
Jennifer R. Lukes ◽  
Hongliang Zhong
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Dynamics Simulation ◽  
Single Wall Carbon Nanotubes ◽  
Heat Current ◽  
Single Wall Carbon ◽  
Simulation Methodology

Despite the significant amount of research on carbon nanotubes, the thermal conductivity of individual single-wall carbon nanotubes has not been well established. To date only a few groups have reported experimental data for these molecules. Existing molecular dynamics simulation results range from several hundred to 6600 W∕m K and existing theoretical predictions range from several dozens to 9500 W∕m K. To clarify the several-order-of-magnitude discrepancy in the literature, this paper utilizes molecular dynamics simulation to systematically examine the thermal conductivity of several individual (10, 10) single-wall carbon nanotubes as a function of length, temperature, boundary conditions and molecular dynamics simulation methodology. Nanotube lengths ranging from 5 nm to 40 nm are investigated. The results indicate that thermal conductivity increases with nanotube length, varying from about 10 W∕m to 375 W∕m K depending on the various simulation conditions. Phonon decay times on the order of hundreds of fs are computed. These times increase linearly with length, indicating ballistic transport in the nanotubes. A simple estimate of speed of sound, which does not require involved calculation of dispersion relations, is presented based on the heat current autocorrelation decay. Agreement with the majority of theoretical/computational literature thermal conductivity data is achieved for the nanotube lengths treated here. Discrepancies in thermal conductivity magnitude with experimental data are primarily attributed to length effects, although simulation methodology, stress, and intermolecular potential may also play a role. Quantum correction of the calculated results reveals thermal conductivity temperature dependence in qualitative agreement with experimental data.

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