Kinetic study of ion-acoustic waves in non-thermal Vasyliunas–Cairns distributed plasmas

The plasma kinetic theory with Vlasov–Poisson model is taken into account to study the dispersion relation and damping rate of one of the fundamental longitudinal low-frequency mode, i.e., ion-acoustic waves (IAWs) in a hybrid Vasyliunas–Cairns distributed plasma using the 3D Vasyliunas–Cairns distribution function (VCDF) for non-thermal electrons. The longitudinal dielectric response function for ion-acoustic waves in non-thermal plasmas is calculated by considering the electrons as Vasyliunas–Cairns distributed while the ions are taken to be Maxwellian. Both the dispersion and damping rate of IAWs are significantly swayed by the simultaneous presence of two non-thermality parameters ^'α ^' and ^'κ ^' . It is found that the damping rate of IAWs is remarkably higher for Maxwellian distributed electron plasmas in comparison to non-thermal Vasyliunas–Cairns distributed plasmas. The analytical expression of damping rate of IAWs is obtained under weak damping approximation, while numerical plots of strong damping rates (when ion temperature become almost equal to electron temperature) are also obtained using Newton–Raphson method from exact solution of dispersion relation equation obtained from dielectric response function. The results are applicable to space plasma regions where highly energetic particles having VCDF exist.