scholarly journals Experimental Observations of the Diffusion Cooling of Electrons in Argon

1975 ◽  
Vol 28 (6) ◽  
pp. 675 ◽  
Author(s):  
T Rhymes ◽  
RW Crompton
Keyword(s):  
Diffusion Coefficient ◽  
Energy Transfer ◽  
Satisfactory Agreement ◽  
Pressure Dependence ◽  
Pressure Range ◽  
Sampling Technique ◽  
Cooling Effect ◽  
Hydrogen Mixtures ◽  
Gas Molecules

The cooling by diffusion of electrons in argon and in argon–hydrogen mixtures has been studied by the Cavalieri density sampling technique. In the case of argon, the measured values of the reduced diffusion coefficient ND varied by more than a factor of two over the pressure range 2–8 kPa. When small quantities of hydrogen were added to the argon, the cooling effect was reduced due to the increased energy transfer between the electrons and gas molecules. For argon, the magnitude and pressure dependence of ND are in satisfactory agreement with the recent calculations by Leemon and Kumar (1975).

Pressure Dependence of Energy Transfer from Pyrene to Perylene

1972 ◽  
Vol 57 (4) ◽  
pp. 1473-1475 ◽  
Author(s):  
P. C. Johnson ◽  
H. W. Offen
Keyword(s):  
Energy Transfer ◽  
Pressure Dependence

scholarly journals Difference Analysis of Gas Molecules Diffusion Behavior in Natural Ester and Mineral Oil Based on Molecular Dynamic Simulation

Molecules ◽  
2019 ◽  
Vol 24 (24) ◽  
pp. 4463 ◽  
Author(s):  
Wenyu Ye ◽  
Jian Hao ◽  
Yufeng Chen ◽  
Mengzhao Zhu ◽  
Zhen Pan ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Interaction Energy ◽  
Free Volume ◽  
Mean Square Displacement ◽  
Mineral Oil ◽  
Relative Molecular Mass ◽  
Diffusion Behavior ◽  
Influence Of Temperature On ◽  
Gas Molecules ◽  
Natural Ester

Natural ester, as a new environmentally green insulating oil, has been widely used in transformer. In an oil-immersed transformer, the normal aging, thermal failure, and discharge failure could easily lead to the decomposition of the oil-paper insulation system and produce different kinds of gases. Studying gas dissolution in natural ester and mineral oil could provide assistance in applying criteria to make a diagnosis of different kinds of faults in the transformer. In this paper, the molecular dynamics method was used to investigate the diffusion behavior of seven fault characteristic gases (including H2, CO, CH4, C2H2, CO2, C2H4, C2H6) in natural ester and mineral oil. The simulation parameters of free volume, interaction energy, mean square displacement, and diffusion coefficient were compared between the natural ester and mineral oil. Meanwhile, the influence of temperature on the diffusion of gas molecules in two kinds of oils was also analyzed. Results showed that the free volume, the interaction energy, and the relative molecular mass of gas molecules were the factors influenced by the diffusion of gas molecules in natural ester and mineral oil. The order of the diffusion coefficients of gas molecules in natural ester was as follows: H2 > CH4 > CO > C2H2 > C2H4 > CO2 > C2H6 and that in mineral oil was as follows: H2 > CH4 > CO> C2H2 > C2 H4 > C2H6 > CO2. By comparing the diffusion behavior of gas molecules in natural ester and mineral oil, it was found that the smaller free volume and higher interaction energy of gas molecules in natural ester were the major reasons for the gas molecules to be more difficult to diffuse in natural ester. The rising temperature could enhance the free volume and reduce the interaction energy between gas molecules and oil. The diffusion coefficient of gas molecules increased exponentially with the follow of temperature. However, the temperature didn’t affect the ordering of diffusion coefficient, free volume, and interaction energy of gas molecules in natural ester and mineral oil.

Efficiency of Energy Transfer in a Small Plasma Focus Device

2005 ◽  
Vol 107 ◽  
pp. 95-98
Author(s):  
Dusit Ngamrungroj ◽  
Rattachat Mongkolnavin ◽  
Chiow San Wong
Keyword(s):  
Energy Transfer ◽  
Plasma Focus ◽  
Pressure Range ◽  
Initial Energy ◽  
Energy Transfer Efficiency ◽  
Plasma Focus Device ◽  
Transfer Efficiency ◽  
Plasma Dynamics ◽  
Plasma Energy ◽  
Basic Model

A study of energy transfer in a small plasma focus device has been carried out during its axial phase. The snow-plough model has been used in the simulation as a basic model for the calculation of plasma dynamics. The energy transferred to the plasma is calculated by considering the work done by the electromagnetic piston during the axial phase. It was found that the plasma energy calculated by this model agrees well with the experimental data within the pressure range of 1 mbar to 4 mbar if the mass shedding effect is included in the model. According to the present computation, the energy transferred into the plasma, in the case of a plasma focus with 2.3 kJ initial energy operated with nitrogen gas within the pressure range of 1 to 4 mbar, is between 224 J to 250 J. This corresponds to energy transfer efficiency of 9.6% to 10.7%. The mass shedding factor decreases from 0.23 to 0.069 with increasing pressure. Correspondingly, the energy transfer efficiency changes slightly at a higher pressure.

A Molecular Dynamics Study on Pressure Dependence of Ag Diffusion in Ag3SI

2010 ◽  
Vol 72 ◽  
pp. 337-342
Author(s):  
Masakazu Yarimitsu ◽  
Masaru Aniya
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Coefficient ◽  
High Temperature ◽  
Pressure Dependence ◽  
Distribution Functions ◽  
Intermediate Temperature ◽  
Β Phase ◽  
Α Phase ◽  
Method Of Molecular Dynamics ◽  
Pair Distribution Functions

The pressure dependence of the diffusion coefficient in the superionic α- and β-phases of Ag3SI has been studied by using the method of molecular dynamics. It is shown that in the high temperature α-phase, the Ag diffusion coefficient decreases with pressure. On the hand, in the intermediate temperature β-phase, the Ag diffusion coefficient exhibits a maximum at around 2.8 GPa. The structural origin of this behavior is discussed through the pressure dependence of the pair distribution functions.

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