title: Dielectric function of a collisional plasma for arbitrary ionic charge.
abstract: A simple model for the dielectric function of a completely ionized plasma with an arbitrary ionic charge that is valid for long-wavelength high-frequency perturbations is derived using an approximate solution of a linearized Fokker-Planck kinetic equation for electrons with a Landau collision integral. The model accounts for both the electron-ion collisions and the collisions of the subthermal (cold) electrons with thermal ones. The relative contribution of the latter collisions to the dielectric function is treated phenomenologically, introducing some parameter ϰ that is chosen in such a way as to get a well-known expression for stationary electric conductivity in the low-frequency region and fulfill the requirement of a vanishing contribution of electron-electron collisions in the high-frequency region. This procedure ensures the applicability of our model in a wide range of plasma parameters as well as the frequency of the electromagnetic radiation. Unlike the interpolation formula proposed earlier by Brantov et al. [Brantov et al., JETP 106, 983 (2008)], our model fulfills the Kramers-Kronig relations and permits a generalization for the cases of degenerate and strongly coupled plasmas. With this in mind, a generalization of the well-known Lee-More model [Y. T. Lee and R. M. More, Phys. Fluids 27, 1273 (1984)] for stationary conductivity and its extension to dynamical conductivity [O. F. Kostenko and N. E. Andreev, GSI Annual Report No. GSI-2008-2, 2008 (unpublished), p. 44] is proposed for the case of plasmas with arbitrary ionic charge.
authors.affiliation: Theoretical Physics Division, Institute of Radiophysics and Electronics, 0203 Ashtarak, Armenia and Center of Strong Fields Physics, Yerevan State University, 0025 Yerevan, Armenia.
authors.forename: H B
authors.initials: HB
authors.lastname: Nersisyan
authors.affiliation: Joint Institute for High Temperatures RAS, Moscow 125412, Russia.
authors.forename: M E
authors.initials: ME
authors.lastname: Veysman
authors.affiliation: Joint Institute for High Temperatures RAS, Moscow 125412, Russia and Moscow Institute of Physics and Technology (State University), Moscow 113303, Russia.
authors.forename: N E
authors.initials: NE
authors.lastname: Andreev
authors.affiliation: Theoretical Physics Division, Institute of Radiophysics and Electronics, 0203 Ashtarak, Armenia.
authors.forename: H H
authors.initials: HH
authors.lastname: Matevosyan