Scattering processes and electrical conductivity of partially ionized hydrogen plasma

2004

Physics of Plasmas

The polarization bremsstrahlung radiation due to electron-neutral atom scatterings in partially ionized hydrogen plasmas is investigated. A screened polarization potential model is applied to describe the polarization interaction between the projectile electron and the neutral target atom. The classical trajectory analysis is applied to represent the polarization bremsstrahlung radiation cross section as a function of the impact parameter, Debye length, radiation photon energy, and collision energy. The results show that the plasma screening effects on the bremsstrahlung cross section are found to be more significant for the soft photon radiation. It is also found that the bremsstrahlung radiation cross section is significantly increased with the increasing quantum state.

Section: Introductionmentioning

confidence: 99%

Quantum state and screening effects on electron-hydrogen polarization bremsstrahlung in partially ionized plasmas

2004

Physics of Plasmas

“…The plasma described by the standard static DebyeHückel potential has been known as the ideal or weakly coupled classical plasma since the average interaction energy between charged particles is smaller than the average kinetic energy of a plasma particle in plasmas [8,9]. However, it is shown that the static interaction potential would not be reliable to explore the collision and radiation processes in plasmas when the velocity of the projectile is comparable to or smaller than the velocity of the plasma electron since the projectile electron would polarize the surrounding plasma shielding cloud due to the long-duration of the interaction [10]. In these circumstances, the dynamic description of the plasma electrons has to be taken into account in order to properly investigate the influence of the plasma shielding on the effective interaction potential in plasmas.…”

mentioning

confidence: 99%

“…Recently, the dynamic screening length [10] in nonideal plasmas has been obtained as a function of the velocity and temperature such as…”

mentioning

confidence: 99%

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

Zeitschrift Für Naturforschung A

Hong

2013

This paper is dedicated to Professor Alfred Klemm, one of the pioneers in the field of isotope effects and molten salts and the founder of the Zeitschrift für Naturforschung, on the occasion of his 100th birthday.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.Key words: Dynamic Quantum Screening; Transition Bremsstrahlung; Semiclassical Plasma.The bremsstrahlung emission spectrum [1 -7] due to the particle interactions in plasmas has received considerable attention since the bremsstrahlung process has played a crucial role in modern fields of plasma physics, such as plasma diagnostics, plasma discharges, and plasma spectroscopy. In addition to the bremsstrahlung emission by the electron-ion encounters, the transition bremsstrahlung process [3,6] due to the polarization interaction between the plasma particle and the Debye shielding cloud in plasmas has been extensively investigated since this process has provided useful information on the physical properties of the screening structure and plasma parameters. The plasma described by the standard static DebyeHückel potential has been known as the ideal or weakly coupled classical plasma since the average interaction energy between charged particles is smaller than the average kinetic energy of a plasma particle in plasmas [8,9]. However, it is shown that the static interaction potential would not be reliable to explore the collision and radiation processes in plasmas when the velocity of the projectile is comparable to or smaller than the velocity of the plasma electron since the projectile electron would polarize the surrounding plasma shielding cloud due to the long-duration of the interaction [10]. In these circumstances, the dynamic description of the plasma electrons has to be taken into account in order to properly investigate the influence of the plasma shielding on the effective interaction potential in plasmas. In addition to the dynamic screen-

“…Hence, the expression of the bremsstrahlung crosssection [equation (11)] would be reliable to investigate the low-energy bremsstrahlung process due to the polarization interactions in nonideal plasmas. Very recently, an excellent discussion on the Gaunt factor and comparisons for the bremsstrahlung calculations by using various methods such as Born, Kramers, and Sommerfeld were given by Fortmann, Redmer, Reinholz, Röpke, Wierling, and Rozmus [16].…”

mentioning

confidence: 99%

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

Kim¹,

Zeitschrift Für Naturforschung A

2009

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.Key words: Transition Bremsstrahlung; Nonideal Plasmas.The bremsstrahlung process [1 -3] has been of great interest since this process is one of the most fundamental processes in many areas of physics such as astrophysics, atomic physics, and plasma physics. In addition, the inverse process to the bremsstrahlung has been also of interest, especially in astrophysical plasmas [1]. The transition bremsstrahlung or socalled polarization bremsstrahlung [4 -6] in plasmas, due to the interaction between the Debye shielding cloud and plasma particle, has been extensively investigated in weakly and strongly coupled plasmas since this process has provided useful information on various plasma parameters. For low-energy electron encounters, the transition bremsstrahlung is expected to be significant due to the long collision time between the projectile electron and induced polarization charge in the Debye shielding cloud. The plasma described by the Debye-Hückel model has been classified as the ideal plasma since the average interaction energy between charged particles is quite smaller than the average kinetic energy of a particle [7]. Moreover, the multiparticle correlation effects caused by simultaneous interactions of charged particles should be taken into account with increasing the plasma density. In plasmas with moderate densities and temperatures, the potential energy would not be well characterized by the conventional Debye-Hückel model due to the strong col-0932-0784 / 09 / 0100-0049 $ 06.00 c 2009 Verlag der Zeitschrift für Naturforschung, Tübingen · http://znaturforsch.com lective effects of nonideal particle interactions [8 -11]. Hence, it is expected that the transition bremsstrahlung processes in nonideal plasmas would be quite different from those in ideal plasmas. Thus, we now will investigate the nonideal collective effects on the transition bremsstrahlung due to the polarization interaction between the projectile electron and Debye shielding cloud of an ion in a nonideal plasma using the effective pseudopotential model and taking into account the collective and plasma screening effects since theoretical atomic spectroscopy is crucial to...