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

Abstract

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...