Effects of Grain Size on the Bremsstrahlung Spectrum of Electron-Dust Grain Collisions in Dusty Plasmas

2009 ◽  
Vol 64 (3-4) ◽  
pp. 229-232
Author(s):  
Seo-Hee Kim ◽  
Young-Dae Jung
Keyword(s):  
Grain Size ◽  
Cross Section ◽  
Dusty Plasmas ◽  
Bremsstrahlung Spectrum ◽  
Final States ◽  
Bremsstrahlung Radiation ◽  
Dust Charge ◽  
Bremsstrahlung Emission ◽  
Debye Radius ◽  
Dust Grain

Abstract The grain size effects on the bremsstrahlung emission spectrum due to nonrelativisitc electrondust grain collisions are investigated in dusty plasmas. Using the Born approximation for the initial and final states of the projectile electron, the bremsstranhlung radiation cross section is obtained as a function of the grain size, dust charge, Debye radius, collision energy, and radiation photon energy. It is found that the effects of the grain size enhance the bremsstrahlung radiation cross section, especially for soft-photon radiations. The effect of the Debye radius on the bremsstrahlung cross section is found to be increased with an increase of the magnitude of the charge number of the dust grain. In addition, the grain size effect on the bremsstrahlung spectrum is found to be more significant for highly charged dusty grains

Collective Effects on the Transition Bremsstrahlung Spectrum due to the Polarization Interaction in Nonideal Plasmas

2009 ◽  
Vol 64 (1-2) ◽  
pp. 49-53
Author(s):  
Hwa-Min Kim ◽  
Young-Dae Jung
Keyword(s):  
Cross Section ◽  
Impact Parameter ◽  
Photon Energy ◽  
Parameter Analysis ◽  
Collective Effects ◽  
Bremsstrahlung Spectrum ◽  
Collective Effect ◽  
Bremsstrahlung Radiation ◽  
Polarization Interaction ◽  
Nonideal Plasmas

The collective effects on the transition bremsstrahlung spectrum due to the polarization interaction between the electron and Debye shielding cloud of an ion are investigated in nonideal plasmas. The impact parameter analysis with the effective pseudopotential model taking into account the nonideal collective and plasma screening effects is applied to obtain the bremsstrahlung radiation cross-section as a function of the nonideality plasma parameter, Debye length, photon energy, and projectile energy. It is shown that the collective effects enhance the bremsstrahlung radiation cross-section and decrease with increasing impact parameter. It is also shown that the collective effect is the most significant near the maximum position of the bremsstrahlung cross-section. In addition, it is shown that the collective effect decreases with an increase of the radiation photon energy

scholarly journals Effect of Coulomb Focusing on the Electron–Atom Bremsstrahlung Cross Section for Tungsten and Iron in Nonthermal Lorentzian Plasmas

2020 ◽  
Vol 10 (14) ◽  
pp. 4832
Author(s):  
Myoung-Jae Lee ◽  
Naoko Ashikawa ◽  
Young-Dae Jung
Keyword(s):  
Cross Section ◽  
Atomic Charge ◽  
Bremsstrahlung Spectrum ◽  
Nonthermal Electron ◽  
Emission Rates ◽  
Focusing Effect ◽  
Nonthermal Electrons ◽  
Electron Atom ◽  
Bremsstrahlung Emission ◽  
Bremsstrahlung Process

The Coulomb focusing effect on the electron–atom bremsstrahlung spectrum is investigated in nonthermal Lorentzian plasmas. The universal expression of the cross section of nonrelativistic electron–atom bremsstrahlung process is obtained by the solution of the Thomas-Fermi equation with the effective atomic charge. The effective Coulomb focusing for the electron–atom bremsstrahlung cross section near the threshold domain is also investigated by adopting the modified Elwert-Sommerfeld factor with the mean effective charge for the bremsstrahlung process. In addition, the bremsstrahlung emission rates are obtained by considering encounters between nonthermal electrons and atoms such as Fe and W atoms. We found that the bremsstrahlung emission rates for nonthermal electron–atoms are lower than those for thermal plasmas. Various nonthermal effects on the bremsstrahlung emission rates in Lorentzian plasmas are also discussed.

Small-amplitude electrostatic solitary waves in a dusty plasma with variable charge resonant trapped dust particles

2007 ◽  
Vol 73 (6) ◽  
pp. 901-910 ◽  
Author(s):  
LEILA AIT GOUGAM ◽  
MOULOUD TRIBECHE ◽  
FAWZIA MEKIDECHE
Keyword(s):  
Solitary Waves ◽  
Small Amplitude ◽  
Charge Trapping ◽  
Dusty Plasmas ◽  
Dust Particles ◽  
Plasma Parameters ◽  
Variable Charge ◽  
Dust Charge ◽  
Temperature Equilibrium ◽  
Dust Grain

AbstractSmall-amplitude electrostatic solitary waves are investigated in unmagnetized dusty plasmas with variable charge resonant trapped dust particles. It is found that under certain conditions spatially localized structures, the height and nature of which depend sensitively on the plasma parameters, can exist. The effects of dust grain temperature, equilibrium dust charge, trapping parameter, and dust size on the properties of these solitary waves are briefly discussed. A neural network with a given architecture and learning process, and which may be useful to interpret experimental data, is outlined. Our investigation may be taken as a prerequisite for the understanding of the solitary dust waves that may occur in space as well as in laboratory plasmas.

Influence of the Dynamic Quantum Shielding on the Transition Bremsstrahlung Spectrum and the Gaunt Factor in Strongly Coupled Semiclassical Plasmas

2013 ◽  
Vol 68 (1-2) ◽  
pp. 165-171 ◽  
Author(s):  
Young-Dae Jung ◽  
Woo-Pyo Hong
Keyword(s):  
Cross Section ◽  
Impact Parameter ◽  
Thermal Energy ◽  
Parameter Analysis ◽  
Projectile Energy ◽  
Bremsstrahlung Spectrum ◽  
Bremsstrahlung Radiation ◽  
Screening Effect ◽  
Strongly Coupled ◽  
Dynamic Screening

The influence of the dynamic quantum shielding on the transition bremsstrahlung spectrum is investigated in strongly coupled semiclassical plasmas. The effective pseudopotential and the impact parameter analysis are employed to obtain the bremsstrahlung radiation cross section as a function of the de Broglie wavelength, Debye length, impact parameter, radiation photon energy, projectile energy, and thermal energy. The result shows that the dynamic screening effect enhances the transition bremsstrahlung radiation cross section. It is found that the maximum position of the transition bremsstrahlung process approaches to the center of the shielding cloud with increasing thermal energy. It is also found that the dynamic screening effect on the bremsstrahlung radiation cross section decreases with an increase of the quantum character of the semiclassical plasma. In addition, it is found that the peak radiation energy increases with an increase of the thermal energy. It is also found that the dynamic quantum screening effect enhances the bremsstrahlung Gaunt factor, especially for the soft-photon case.

Bremsstrahlung emission from ion–dust grain Coulomb scatterings in dusty plasmas

2000 ◽  
Vol 7 (2) ◽  
pp. 715-718
Author(s):  
Young-Dae Jung ◽  
Hiro Tawara
Keyword(s):  
Dusty Plasmas ◽  
Bremsstrahlung Emission ◽  
Dust Grain

Size Effects on the Scattering of Electron and Spherical Dust Grain in Dusty Plasmas

2010 ◽  
Vol 65 (12) ◽  
pp. 1147-1150
Author(s):  
Dae-Han Ki ◽  
Young-Dae Jung
Keyword(s):  
Size Effect ◽  
Cross Section ◽  
Size Effects ◽  
Debye Length ◽  
Dusty Plasmas ◽  
Scattering Cross Section ◽  
Charged Dust ◽  
Scattering Cross ◽  
Dust Grain ◽  
The Impact

The finite size effects of the charged dust grain on the electron-dust grain collisions are investigated in complex dusty plasmas. The stationary phase analysis and the effective potential due to the renormalized dust charge are employed to obtain the phase shift for the scattering of the electron and the spherically charged dust grain as a function of the impact parameter, collision energy, Debye length, and dust radius. It is found that the size effect of the dust grain enhances the electron-dust grain scattering cross section in dusty plasmas. It is also found that the size effect on the scattering cross section increases with increasing plasma density. In addition, it is found that the size effect on the electron-dust scattering cross section decreases with an increase of the plasma temperature.

scholarly journals Experimental and Numerical Investigation of the ECAP Processed Copper: Microstructural Evolution, Crystallographic Texture and Hardness Homogeneity

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 607
Author(s):  
A. I. Alateyah ◽  
Mohamed M. Z. Ahmed ◽  
Yasser Zedan ◽  
H. Abd El-Hafez ◽  
Majed O. Alawad ◽  
...  
Keyword(s):  
Grain Size ◽  
Equal Channel Angular Pressing ◽  
Cross Section ◽  
Room Temperature ◽  
Pure Copper ◽  
High Density ◽  
Ecap Processing ◽  
Heterogeneous Distribution ◽  
Angular Pressing ◽  
Average Grain Size

The current study presents a detailed investigation for the equal channel angular pressing of pure copper through two regimes. The first was equal channel angular pressing (ECAP) processing at room temperature and the second was ECAP processing at 200 °C for up to 4-passes of route Bc. The grain structure and texture was investigated using electron back scattering diffraction (EBSD) across the whole sample cross-section and also the hardness and the tensile properties. The microstructure obtained after 1-pass at room temperature revealed finer equiaxed grains of about 3.89 µm down to submicrons with a high density of twin compared to the starting material. Additionally, a notable increase in the low angle grain boundaries (LAGBs) density was observed. This microstructure was found to be homogenous through the sample cross section. Further straining up to 2-passes showed a significant reduction of the average grain size to 2.97 µm with observable heterogeneous distribution of grains size. On the other hand, increasing the strain up to 4-passes enhanced the homogeneity of grain size distribution. The texture after 4-passes resembled the simple shear texture with about 7 times random. Conducting the ECAP processing at 200 °C resulted in a severely deformed microstructure with the highest fraction of submicron grains and high density of substructures was also observed. ECAP processing through 4-passes at room temperature experienced a significant increase in both hardness and tensile strength up to 180% and 124%, respectively.

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