Transport coefficients in standard Kappa distributed plasmas: a comparative study

Abstract. This study systematically derives transport coefficients – electrical conductivity, thermoelectric, diffusion, and mobility – for a Lorentz plasma described by a standard Kappa distribution function. Within the five-moment transport framework, the standard Kappa distribution serves as the zeroth-order function. Momentum and energy collision terms are obtained via the Boltzmann collision integral for Coulomb, hard-sphere, and Maxwell molecule interactions, and incorporated into the momentum equation to formulate generalized Ohm's and extended Fick's laws, yielding the transport coefficients. This study also compares the standard Kappa, modified Kappa, and Maxwellian distributions in terms of their influence on plasma behavior. The results show that for velocity-dependent collisions, such as Coulomb collisions, significant differences arise between the standard and modified Kappa distributions. For low kappa parameter κ values, the standard Kappa distribution reduces collision frequency and thermalization, making it suitable for collisionless or weakly collisional plasmas. In contrast, the modified Kappa distribution increases these effects, indicating its relevance for more collisional environments. Consequently, in Coulomb collisions, the standard distribution weakens momentum and energy exchange compared to the Maxwellian case, while the modified distribution enhances them. Transport properties are also affected differently: as κ decreases, the standard distribution enhances conductivity, mobility, diffusion, and thermoelectric effects, whereas the modified distribution reduces conductivity, mobility, and diffusion, with no change in the thermoelectric coefficient.