Vladimir I. Kogan

Reduced models of the dynamics of light impurity stripping

Abstract“Closed” and “open” reduced models of two or three most abundant light impurity ions in an optically thin hydrogen plasma are considered. The models are shown to satisfactorily describe the average ion charge and radiative losses within a wide range of parameters typical of laboratory and astrophysical plasmas, including the case when the relaxation time of the impurity distribution over ionization states is comparable to or longer than the characteristic times of the most important dynamic processes. The potentialities of the models are demonstrated using the carbon impurity as an example. The models proposed make it possible to analytically study the dynamics of a radiating plasma, obtain qualitatively new results, and significantly reduce the computation time when solving complicated self-consistent dynamical problems.

The Bloch‐Elwert structure as a universal manifestation of the rate of ‘‘Soft’’ inelastic collisions in plasmas: Bremsstrahlung, electrical conductivity, ionization loss

The interrelation is traced and a mutual intrinsic identity at the ‘‘model‐level’’ is demonstrated between various plasma phenomena governed by distant electron‐ion collisions whose rates’ dependencies on the Coulomb parameter Ze2/ℏv are described by a single universal ‘‘Bloch‐Elwert structure’’ (BES) namely low‐frequency Bremsstrahlung, electrical conductivity, and ionization loss of fast particles. In connection with the fact that the original derivation of the BES has been performed by the impact‐parameter (ρ) method which in turn caused a sort of a ‘‘Bohr‐Bloch controversy’’ the Eikonal Approximation of quantum mechanics is invoked which provides a consistent and lucid quantum‐mechanical interpretation of ρ and its extremes ρmin and ρmax thus resolving the above‐mentioned controversy.