The characteristics of ion acoustic solitons in nonthermal regularized kappa distributed plasmas

Abstract

Nonthermal equilibrium is an intrinsic characteristic of space and astrophysical plasmas, and in many space environments, the velocity distributions of charged particles with suprathermal tails may be well be fitted by the Kappa function, which becomes the Maxwellian distribution for κ→∞. Various studies of ion or dusty acoustic solitons, thus, have considered the Kappa distributed electrons in the model calculations. However, the Kappa velocity distribution (KVD) is theoretically not applicable for κ≤3/2. Alternatively, the recently proposed regularized Kappa distribution with two free parameters, κ and α, have been shown to be mathematically and physically smooth for all κ values, which may recover the standard KVD for α=0 and the Maxwellian distribution for κ→∞ and α=0. In this study, we examine the characteristics of ion acoustic solitons based on the linear, weakly nonlinear Korteweg–de Vries (KdV) and fully nonlinear theories with the regularized Kappa distributed electrons and warm ion fluids. These approaches may give rise to the dispersion relation with modified characteristic speed of acoustic waves, the analytical KdV solutions, and the Sagdeev's potential as well as the fully nonlinear solutions. It is shown that the model results are mathematically and physically valid for κ≤3/2 and the formulations with the charges being free parameters are applicable for general acoustic solitons.