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

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.

Dynamically Screened Elastic Collisions in Nonideal Plasmas

2006 ◽  
Vol 61 (7-8) ◽  
pp. 330-334
Author(s):  
Dong-Man Chang ◽  
Won-Seok Chang ◽  
Young-Dae Jung
Keyword(s):  
Cross Section ◽  
Impact Parameter ◽  
Thermal Energy ◽  
Collision Energy ◽  
Debye Length ◽  
Parameter Analysis ◽  
Ion Collisions ◽  
Dynamic Screening ◽  
Nonideal Plasmas ◽  
The Impact

The dynamic screening effects on elastic electron-ion collisions are investigated in nonideal plasmas. The second-order eikonal method with the impact parameter analysis is employed to obtain the eikonal phase as a function of the impact parameter, collision energy, thermal energy, and Debye length. The result shows that the eikonal phase decreases with increasing the thermal energy. It is also found that the dynamic screening effects on the eikonal phase are more significant for large impact parameters. The total eikonal cross section is also found to be decreased with increasing the thermal energy. It is important to note that the eikonal cross section and the eikonal phase including the dynamic screening effects are found to be greater than those including the static screening effects.

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

scholarly journals Nonideal effects on inelastic Compton scattering in a nonideal plasma

2002 ◽  
Vol 67 (2-3) ◽  
pp. 175-182 ◽  
Author(s):  
YOUNG-DAE JUNG
Keyword(s):  
Compton Scattering ◽  
Cross Section ◽  
Debye Length ◽  
Transition Matrix Element ◽  
Collective Effects ◽  
Nonideal Plasma ◽  
Collective Effect ◽  
Photon Process ◽  
The Cross ◽  
Hydrogenic Ions

Inelastic Compton scattering of photons by hydrogenic ions in a classical nonideal plasma is investigated. An effective pseudopotential model taking into account plasma screening and collective effects is applied to describe the interaction potential in a nonideal plasma. The screened atomic wave functions and energy eigenvalues for the ground and excited states of the hydrogenic ion in a classical nonideal plasma obtained by the Ritz variational and perturbational methods. The expression for the lowest-order transition matrix element is obtained by a two-photon process associated with terms quadratic in the vector potential A. The inelastic Compton scattering cross-section horn the 1s ground state to the 2p excited state is obtained as a function of the incident photon energy, Debye length, and the non-ideality plasma parameter. It is found that the collective effect reduces the cross-section. The collective effect on the cross-section is decreased with increasing Debye length.

scholarly journals Classical bremsstrahlung radiation from electron–ion encounters in a nonideal plasma

2002 ◽  
Vol 67 (2-3) ◽  
pp. 191-197
Author(s):  
YOUNG-DAE JUNG ◽  
CHANG-GEUN KIM
Keyword(s):  
Cross Section ◽  
Debye Length ◽  
Collective Effects ◽  
Projectile Energy ◽  
Nonideal Plasma ◽  
Bremsstrahlung Radiation ◽  
Hyperbolic Orbit ◽  
Classical Electron ◽  
Bremsstrahlung Process ◽  
Plasma Effect

The classical electron–ion Coulomb bremsstrahlung process is investigated in a nonideal plasma. An effective pseudopotential model taking into account plasma-screening and collective effects is applied to describe the electron-ion interaction potential in a nonideal plasma. The screened hyperbolic-orbit trajectory method is applied to the motion of the projectile electron in order to investigate the bremsstrahlung radiation cross-section as a function of the scaled impact parameter, eccentricity, nonideal-plasma parameter, Debye length, projectile energy, and photon energy. It is found that the collective effect reduces the bremsstrahlung radiation cross-section on both the soft- and hard-photon cases. For small impact parameters, the nonideal-plasma effect on the bremsstrahlung radiation cross-section is found to be quite small. It is also found that the maximum position of the bremsstrahlung radiation cross-section gets closer to the target ion with increasing nonideal-plasma effect.

Evidence for the Photoemission Nature of Gd 4f Resonant Photoemission

1998 ◽  
Vol 524 ◽  
Author(s):  
S. R. Mishra ◽  
T. R. Cummins ◽  
W. J. Gammon ◽  
G. D. Waddill ◽  
G. Van der-Laan ◽  
...  
Keyword(s):  
Angular Distribution ◽  
Cross Section ◽  
Photon Energy ◽  
Photoelectron Spectroscopy ◽  
Emission Cross Section ◽  
Linear Dichroism ◽  
Constructive Interference ◽  
Resonant Photoemission ◽  
Magnetic Linear Dichroism ◽  
Spectroscopy Experiment

ABSTRACTThe constructive interference between direct and indirect channels above the absorption threshold of a core level leads to a massive increase in the emission cross section leading to a phenomenon called “resonant photoemission”. Using novel magnetic linear dichroism in angular distribution photoelectron spectroscopy experiment we have tried to understand the nature of the resonant photoemission process in Gd metal. The presence of dichroism in Gd 4f photoemission intensity at a photon energy corresponding to resonant photoemission clearly demonstrates the photoemission-like nature of the resonant photoemission process.

Dependence of the optical cross section of interface states on the photon energy at Si-SiO2 structures

1986 ◽  
Vol 168 (1-3) ◽  
pp. 665-671 ◽  
Author(s):  
A. Herms ◽  
J.R. Morante ◽  
J. Samitier ◽  
A. Cornet ◽  
P. Cartujo ◽  
...  
Keyword(s):  
Cross Section ◽  
Photon Energy ◽  
Interface States ◽  
Optical Cross Section

Inhibition of—But Not between—Orientation Detectors: A Theoretical Note on Illusions of Direction

1980 ◽  
Vol 50 (1) ◽  
pp. 255-262 ◽  
Author(s):  
Willard L. Brigner
Keyword(s):  
Lateral Inhibition ◽  
Single Stimulus ◽  
Single Line ◽  
Collective Effects ◽  
Collective Effect ◽  
Stimulus Line ◽  
Model Based ◽  
Multiple Stimulus

In accounting for illusions of direction, many current models assume lateral inhibition among orientation detectors; however, that assumption is unnecessary. Rather, the illusions can be predicted by a model based on the pattern of inhibition and excitation across orientation detectors as caused by a single stimulus line. From the collective effects of multiple stimulus lines, a pattern of excitation and inhibition results which is perceived as an illusion of direction. This collective effect is predicted by convoluting a function representing physical orientation of stimulus lines with a function representing the pattern of inhibition and excitation elicited by a single line. Both perceived angle-expansion (repulsion) and perceived angle-contraction (attraction) are generated by the model.

scholarly journals Non-Markovian Quantum Optics with Three-Dimensional State-Dependent Optical Lattices

Quantum ◽  
2018 ◽  
Vol 2 ◽  
pp. 97 ◽  
Author(s):  
A. González-Tudela ◽  
J. I. Cirac
Keyword(s):  
Quantum Optics ◽  
Spectral Density ◽  
Long Range ◽  
Photon Energy ◽  
Optical Lattices ◽  
Cold Atoms ◽  
Three Dimensional ◽  
Collective Effects ◽  
State Dependent ◽  
Anisotropic Interactions

Quantum emitters coupled to structured photonic reservoirs experience unconventional individual and collective dynamics emerging from the interplay between dimensionality and non-trivial photon energy dispersions. In this work, we systematically study several paradigmatic three dimensional structured baths with qualitative differences in their bath spectral density. We discover non-Markovian individual and collective effects absent in simplified descriptions, such as perfect subradiant states or long-range anisotropic interactions. Furthermore, we show how to implement these models using only cold atoms in state-dependent optical lattices and show how this unconventional dynamics can be observed with these systems.

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