Kinetic instability of twisted ion-acoustic mode with superthermal species of plasma

The electrostatic twisted ion-acoustic waves with finite orbital angular momentum states and associated kinetic instability are investigated in an electron-ion plasma. The plasma consisting of superthermal electrons and ions is modeled by using a non-gyrotropic Kappa distribution function in which the free energy source for wave excitation is provided by the relative directed motion of streaming electrons with respect to the ions. In the frame work of kinetic theory, the VlasovPoisson equations are employed to derive the expressions for dispersion relation and Landau damping rate under paraxial approximation. The results are analyzed for threshold condition of wave dispersion and instability growth rate in the presence of helical electric field structure. The relevance of study to the observed situations is also described.