scholarly journals Stopping power of a helium plasma under LTE or NLTE conditions

2018 ◽  
Vol 36 (4) ◽  
pp. 442-447
Author(s):  
Luis González-Gallego ◽  
Manuel D. Barriga-Carrasco ◽  
Juan Miguel Gil ◽  
Rafael Rodríguez ◽  
Guadalupe Espinosa
Keyword(s):  
Theoretical Model ◽  
Electron Temperature ◽  
Thermal Equilibrium ◽  
Stopping Power ◽  
Local Thermal Equilibrium ◽  
Helium Plasma ◽  
Slowing Down ◽  
Non Local ◽  
Argon Ions ◽  
Bound Electrons

AbstractIn this work, the stopping power of a partially ionized helium plasma due to its free and bound electrons is analyzed for an electron temperature and density in which local thermal equilibrium (LTE) or non-local thermal equilibrium (NLTE) regimes can be possible. In particular by means of collisional-radiative models, the average ionization of the plasma as well as the abundances of different helium species (HeI, HeII, and HeIII) are analyzed in both LTE and NLTE thermodynamic states. The influence of this ionization and of the different ion abundances on the stopping power of the helium plasma is shown to be quite significant. Finally, our theoretical model is compared with experimental results on slowing down of swift argon ions in helium plasma.

Heat-Transfer Study of Aluminum-Foam Heat Sink for Electronic Cooling

Volume 4 ◽  
2004 ◽  
Author(s):  
W. H. Hsieh ◽  
J. Y. Wu ◽  
W. H. Shih ◽  
W. C. Chiu
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Temperature Difference ◽  
Heat Sink ◽  
Thermal Equilibrium ◽  
Aluminum Foam ◽  
Local Thermal Equilibrium ◽  
Pore Density ◽  
Gas Phases ◽  
Non Local

The demand of high speed and miniaturization of electronic components results in increased power dissipation requirement for thermal management. In this work, the effects of porosity (ε), pore density (PPI) and air velocity on the heat-transfer characteristics of aluminum-foam heat sinks are investigated experimentally. The phenomenon of non-local thermal equilibrium (NLTE) is also observed and reported. Results show that the Nu increases as the pore density increases, due to the fact that aluminum foam with a larger pore density has a larger heat-transfer area. The Nusselt number also increases with the increase of porosity due to the same reason. It is noted that temperatures of the solid and gas phases of the aluminum foam decrease as Reynolds number increases, caused by the increased convective heat-transfer rate at higher Reynolds number. The deduced temperature difference between solid and gas phases clearly indicates the existence of non-local thermal equilibrium condition within the aluminum-foam heat sink. The increase of the porosity and the pore density enhances the phenomenon of non-local thermal equilibrium. The temperature difference increases with the decrease of Reynolds number and the distance away from the heat source.

The isentropic exponent of non-local thermal equilibrium plasmas

2002 ◽  
Vol 294 (1) ◽  
pp. 47-51 ◽  
Author(s):  
K.T.A.L Burm ◽  
W.J Goedheer ◽  
D.C Schram
Keyword(s):  
Thermal Equilibrium ◽  
Local Thermal Equilibrium ◽  
Isentropic Exponent ◽  
Non Local

Formulation and Numerical Solution of Non-Local Thermal Equilibrium Equations for Multiple Gas/Solid Porous Metal Hydride Reactors

2000 ◽  
Vol 123 (3) ◽  
pp. 520-526 ◽  
Author(s):  
George M. Lloyd ◽  
A. Razani ◽  
Kwang J. Kim
Keyword(s):  
Boundary Conditions ◽  
Metal Hydride ◽  
Thermal Equilibrium ◽  
Porous Metal ◽  
High Energy ◽  
Local Thermal Equilibrium ◽  
Equilibrium Equations ◽  
Interphase Heat Transfer ◽  
Non Local ◽  
Coupled Reactors

The assumption of local thermal equilibrium (LTE) is very common in the study of reacting flows in porous media. The assumption simplifies the structure of the solutions and places fewer constraints on computational methods for the domain and boundary conditions. However, in certain systems, such as gas/solid metal hydride reactors, the boundary conditions may impose high energy transfer rates which produce slowly evolving phase change fronts coupled with rapid kinetics. Overall performance of the systems is proportional to the release or absorption of hydrogen, and this is sensitively related to temperature. Thus, capturing local departures from LTE is required. This paper directly evaluates the influence of these effects by solving an NLTE (non-local thermal equilibrium) formulation for coupled reactors as a function of the interphase heat transfer coefficient, hsf. The reactor dynamics and overall energy balances are compared to solutions previously obtained from LTE calculations. The results appear to be the first NLTE results for coupled reactors. They confirm the existence of NLTE effects and suggest the magnitude of hsf for which they can be minimized.

scholarly journals Measurement of stopping power of 240 MeV argon ions in partially ionized helium discharge plasma

2000 ◽  
Vol 18 (4) ◽  
pp. 647-653 ◽  
Author(s):  
M. OGAWA ◽  
U. NEUNER ◽  
H. KOBAYASHI ◽  
Y. NAKAJIMA ◽  
K. NISHIGORI ◽  
...  
Keyword(s):  
Energy Loss ◽  
Electron Density ◽  
Target Thickness ◽  
Stopping Power ◽  
Helium Plasma ◽  
Discharge Ignition ◽  
The Mean ◽  
Argon Ions ◽  
Partially Ionized ◽  
Mean Charge

An energy loss of 240 MeV argon ions in a Z-pinch helium plasma has been for the first time observed throughout the entire pinching process. Standard Stark broadening analysis gives an electron density ranging from 4 to 6 × 1017 cm−3 during the pinch. To deduce stopping power from the energy loss, the target thickness of the helium plasma has been evaluated assuming the mean charge of helium based on thermal equilibrium. The observed electron density and the mean charge of helium give a target thickness of 30 ± 3 μg cm−2 from 1 μs to 1.8 μs after the discharge ignition. The measured stopping power exceeds a tabulated value for cold helium gas by a factor of 2 to 3 around the time of the first pinch. The experimental stopping power is compared with theoretical values calculated using an equation of stopping power for a partially ionized plasma.

scholarly journals On the Thermodynamic Origin of Gravitational Force by Applying Spacetime Entanglement Entropy and the Unruh Effect

Entropy ◽  
2019 ◽  
Vol 21 (3) ◽  
pp. 296
Author(s):  
Shujuan Liu ◽  
Hongwei Xiong
Keyword(s):  
Theoretical Model ◽  
Thermal Equilibrium ◽  
Gravitational Force ◽  
Entanglement Entropy ◽  
Quantum Fluctuations ◽  
Local Thermal Equilibrium ◽  
Unruh Effect

We consider the thermodynamic origin of the gravitational force of matter by applying the spacetime entanglement entropy and the Unruh effect originating from vacuum quantum fluctuations. By analyzing both the local thermal equilibrium and quasi-static processes of a system, we may get both the magnitude and direction of Newton’s gravitational force in our theoretical model. Our work shows the possibility that the elusive Unruh effect has already shown its manifestation through gravitational force.

scholarly journals Modelling the non-local thermodynamic equilibrium spectra of silylene SiH2

2021 ◽  
Author(s):  
Victoria H.J. Clark ◽  
Sergey N Yurchenko
Keyword(s):  
Thermodynamic Equilibrium ◽  
Thermal Equilibrium ◽  
Local Thermodynamic Equilibrium ◽  
Polyatomic Molecules ◽  
Local Thermal Equilibrium ◽  
Non Local

This paper sets out a robust methodology for modelling spectra of polyatomic molecules produced in reactive or dissociative environments, with vibrational populations outside local thermal equilibrium (LTE). The methodology is...

Arc facility for investigating non‐local thermal equilibrium plasmas

1986 ◽  
Vol 57 (8) ◽  
pp. 2093-2095 ◽  
Author(s):  
A. Sedghinasab ◽  
T. L. Eddy ◽  
R. T. Murray ◽  
A. V. Larson
Keyword(s):  
Thermal Equilibrium ◽  
Local Thermal Equilibrium ◽  
Non Local
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