Effect of anisotropy of lighter and heavier ions on solitary waves in a multi-ion plasma

We have studied the combined effect of the pressure anisotropies of lighter and heavier ions of opposite polarities on solitary waves in a plasma composed of these ions as well as kappa described electrons of solar and cometary origin. Using the theory of Chew, Goldberger, and Low (the CGL theory), the anisotropies of all three ions have been included in the derivation of the Zakharov–Kuznetsov equation. The effects of various combinations of pressure anisotropies of both lighter as well as heavier ions of opposite polarities have been considered. From the figures, plotted for parameters observed at comet Halley, it is seen that different properties of the solitary wave such as width and amplitude, as well as dispersion and nonlinear coefficients, are profoundly affected by the anisotropies of the ions. Also, the pressure anisotropy of the lighter ions determines the polarity of the solitary waves: the plasma supports compressive (rarefactive) solitary waves when the lighter ions are pressure isotropic (anisotropic).