An investigation into the Coulomb logarithm models and their effects on the electron heat transfer in warm dense plasmas
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ORIGINAL PAPER
An investigation into the Coulomb logarithm models and their effects on the electron heat transfer in warm dense plasmas M Oloumi, M Habibi and H Hosseinkhani* Plasma and Nuclear Fusion Research School, Nuclear Science and Technology Research Institute, Tehran 14399-51113, Iran Received: 26 January 2020 / Accepted: 05 June 2020
Abstract: A comparison study of various models in investigating the Coulomb logarithm (CL) for a wide range of densities and temperatures is carried out. Using two known reference parameters, the ion coupling C and the electron degeneracy H, the capability of a recently proposed coupled Gericke–Murillo–Schlanges (CGMS) model in evaluating the CL is compared with other previous models—the Gericke–Murillo–Schlanges (GMS) model, the Landau–Spitzer (LS), the Brown–Preston–Singleton (BPS), the classical molecular dynamics (MD), and Khrapak (KH) model. It is observed that the CGMS model shows reliable results in both weakly and strongly coupled regimes. Moreover, the effects of using these models on studying electron heat transfer and conductivity coefficient within the weakly coupled and strongly coupled plasmas are examined. Keywords: Strongly coupled plasmas; Warm dense matter; Coulomb logarithm; Plasma collisions
1. Introduction The hot and dense plasmas are ordinarily shaped through the rapid deposition of energy into a solid target where plasmas gradually develop through a various range of temperature and density. During some advanced experiments, such as the interaction of intense short-pulse lasers or X-ray lasers with matter [1, 2], the compressed matter of inertial confinement fusion (ICF) [3], and laboratory astrophysics [4], it could be probed the warm dense plasmas (WDPs) in which properties of both ideal plasmas and correlated systems are emerged [5]. One of the critical parameters in assessing the transport coefficient in the WDPs is the Coulomb logarithm (CL), which is as well considered as an effective component in fluid simulation codes. From a kinetic point of view, there are different models to investigate such matters and the evaluation of some macroscopic parameters like the CL [6–21]. One of the common models on this subject belongs to Spitzer [12] who considered a Maxwellian distribution of free electrons to examine transport phenomena in fully ionized, non-degenerated plasmas. He introduced a model in the lowdensity regime considering small-angle scattering to avoid
*Corresponding author, E-mail: [email protected]
the integral divergence in binary collisions. It should be noted this estimation fails at higher densities and lower temperatures where the Coulomb logarithm will become less than or equal to zero. Therefore, Spitzer’s model gives the erroneous outcome to calculate the plasma conductivity for solid density plasmas. To transcend this limitation, various improved models of the original Spitzer’s approach have been proposed for a variety of plasma conditions. In the correlated plasmas, a generalized CL is required which asymptotes to ln K
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