Ion mass effects on shock-like structures in multi-species plasma

Abstract

Ion acoustic type shock-like structures based on the extended steady-state theory in multi-species plasma with different ion masses are studied. Using theoretical treatments, three simple models using continuous electron distribution functions at the separatrix , have been considered. From numerical studies on the existence of shock-like structures, we find the lowest limits of propagation velocity and amplitude of shock-like structures as a function of mass ratio (or density). In particle simulations, it is established for the case of a current driven system. Simulations are performed with an axially bounded electrostatic particle-in-cell (PIC) code XPDP1, which is a workstation version of the one-dimensional electrostatic bounded plasma code PDW1 [35-37]. The effect of the massive ion is to decrease the propagating velocity of the shock-like structures and decrease its maximum (or net) amplitude. Also, by increasing the density of the massive ion component, both the velocity of propagation and the maximum (or net) amplitude of the shock-like structure decreases.