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 more significant for low-energy projectiles. It is also found that the static plasma screening formula obtained by the Debye-Huckel model overestimates the plasma screening effects on the atomic excitation processes in dense plasmas. (C) 1997 American Institute of Physics.