Young-Dae Jung

Quantum-mechanical effects on electron–electron scattering in dense high-temperature plasmas

Quantum-mechanical effects on electron–electron scattering cross sections are investigated in dense high-temperature plasmas. An effective pseudopotential model taking into account both quantum-mechanical effects and plasma screening effects is applied to describe electron–electron interactions in dense high-temperature plasmas. The Born approximation and the total spin states are considered to obtain high-energy electron–electron scattering cross sections. The results show that the differential scattering cross sections are significantly reduced with increasing the thermal de Broglie wavelength. It is also found that the quantum-mechanical effects are especially important at the scattering angle θlab=π/4.

Dynamic plasma screening effects on semiclassical inelastic electron–ion collisions in dense plasmas

In dense plasmas, dynamic plasma screening effects are investigated on 1s→2p dipole transition probabilities for electron-impact excitation of hydrogenic ions. The electron–ion interaction potential is considered by introduction of the plasma dielectric function. A semiclassical straight-line trajectory method is applied to the path of the projectile electron in order to visualize the semiclassical transition probability as a function of the impact parameter, projectile energy, and plasma parameters. The transition probability including the dynamic plasma screening effect is always greater than that including the static plasma screening effect. When the projectile velocity is smaller than the electron thermal velocity, the dynamic polarization screening effect becomes the static plasma screening effect. When the projectile velocity is greater than the electron thermal velocity, then the interaction potential is almost unshielded. The difference between the dynamic and static plasma screening effects is mo...

Dynamic screening effects on semiclassical electron captures in kappa-Maxwellian plasmas

Dynamic plasma screening effects on the electron capture process in kappa-Maxwellian plasmas are investigated using the semiclassical version of the Bohr?Lindhard model. The interaction potential and screened electron capture radius are obtained by considering the longitudinal component of the plasma dielectric function. The semiclassical electron capture probability is also obtained as a function of the impact parameter, Debye length, projectile velocity, and spectral index. It is found that the dynamic screening effects on the electron capture probability are more significant for low projectile energies. The maximum position of the scaled electron capture probability approaches the target nucleus with increasing projectile energy. The dynamic screening effect is also found to decrease with increasing spectral index.

Beam excited acoustic instability in semiconductor quantum plasmas

The instability of hole-Acoustic waves due to electron beam in semiconductor quantum plasmas is examined using the quantum hydrodynamic model. The quantum effects are considered including Bohm potential, Fermi degenerate pressure, and exchange potential of the semiconductor quantum plasma species. Our model is applied to nano-sized GaAs semiconductor plasmas. The variation of the growth rate of the unstable mode is obtained over a wide range of system parameters. It is found that the thermal effects of semiconductor species have significance over the hole-Acoustic waves.

Nonthermal and geometric effects on the symmetric and anti-symmetric surface waves in a Lorentzian dusty plasma slab

The nonthermal and geometric effects on the propagation of the surface dust acoustic waves are investigated in a Lorentzian dusty plasma slab. The symmetric and anti-symmetric dispersion modes of the dust acoustic waves are obtained by the plasma dielectric function with the spectral reflection conditions the slab geometry. The variation of the nonthermal and geometric effects on the symmetric and the anti-symmetric modes of the surface plasma waves is also discussed.

Landau damping effects on classical electron–ion Coulomb bremsstrahlung in dense plasmas

Landau damping effects on the classical electron–ion Coulomb bremsstrahlung process in dense Maxwellian plasmas are investigated. The electron–ion dynamic interaction potential is obtained by introduction of the longitudinal plasma dielectric function. The classical trajectory method is applied to represent the differential bremsstrahlung radiation cross section as a function of the impact parameter, photon energy, projectile velocity, electron thermal velocity, and Debye length. The Landau damping effect in the soft photon case is found to be more important than that in the hard photon case. It is also found that the Landau damping effect is important when the projectile velocity is equal to the electron thermal velocity (vT/ve=1), for example, the Landau damping effect is about 3.4% for Ep/Ee=0.1.

Electron-exchange and quantum screening effects on the collisional entanglement fidelity in degenerate quantum plasmas

The influence of electron-exchange and quantum screening on the collisional entanglement fidelity for the elastic electron–ion collision is investigated in degenerate quantum plasmas. The effective Shukla–Eliasson potential and the partial wave method are used to obtain the collisional entanglement fidelity in quantum plasmas as a function of the electron-exchange parameter, Fermi energy, plasmon energy and collision energy. The results show that the quantum screening effect enhances the entanglement fidelity in quantum plasmas. However, it is found that the electron-exchange effect strongly suppresses the collisional entanglement fidelity. Hence, we have found that the influence of the electron-exchange reduces the transmission of quantum information in quantum plasmas. In addition, it is found that, although the entanglement fidelity decreases with an increase of the Fermi energy, it increases with increasing plasmon energy in degenerate quantum plasmas.

K-shell photoionizations in classical nonideal plasmas

Collective and plasma screening effects on photoionization cross sections from the 1s state of hydrogenic ions in classical nonideal plasmas are investigated. An effective pseudopotential model taking into account the collective and plasma screening effects is applied to describe the interaction potential in nonideal plasmas. The screened atomic wave function and energy eigenvalue for the ground state of the hydrogenic ion in classical nonideal plasmas are obtained by the Ritz variational method. The photoionization cross section is obtained by the acceleration form of the transition matrix element in order to investigate the collective and plasma screening effects on the interaction potential. The retardation and Coulomb correction effects are also considered in nonideal plasmas. The total correlation effect is obtained as a function of the nonideality plasma parameter, Debye length, and incident photon energy. The result shows that the collective effect significantly reduces the photoionization cross se...

Rotational Excitations of H2 in Nonthermal Astrophysical Plasmas

This paper investigates the nonthermal effects of electrons on the rotational excitations of the hydrogen molecule in astrophysical Lorentzian plasmas. The J = 0 ? 2 and J = 1 ? 3 rotational excitation cross sections are employed in order to obtain the rotational excitation rates of the hydrogen molecule as functions of the spectral index and temperature. It is shown that the rotational excitation rates of H2 in non-Maxwellian plasmas are smaller than those in Maxwellian plasmas in low-temperature regions (HI region). However, in high-temperature regions the rotational excitation rates of H2 in non-Maxwellian plasmas are greater than those in Maxwellian plasmas. It is found that the rotational excitation temperature for the peak position of the excitation rate decreases with the decreasing nonthermal character of the plasma. It is also shown that the nonthermal effect on the rotational excitation for the principal transition J = 0 ? 2 is stronger than that for the J = 1 ? 3 transition.

Coulomb correction effects on bremsstrahlung spectra from non-Maxwellian plasmas

Coulomb correction effects are investigated on electron–ion bremsstrahlung emission from a non-Maxwellian velocity distribution plasma of the form exp[−(ν/νm)m] where νm2=(3kBTe/Me)Γ(3/m)/Γ(5/m) and 2⩽m⩽5. The bremsstrahlung emission rate is obtained as a function of the photon energy. For soft photon radiations, the Coulomb correction effects on the bremsstrahlung emission rate are found to be more significant for the distribution with m=2, i.e., Maxwellian distribution plasmas. However, for hard photon radiations, the Coulomb correction effects are found to be almost independent of the non-Maxwellian character. Thus, it would be possible to figure out the form of the electron distribution function using hard bremsstrahlung spectra rather than soft bremsstrahlung spectra since the bremsstrahlung emission rate without the Coulomb corrections only depends on the non-Maxwellian character for hard photon radiations.