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 (v 2 = 2φ), 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][36][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.

Theoretical investigation and particle simulation of obliquely propagating nonlinear double layers (NDLs) of nonmonotonic type are performed in a magnetized plasma, which consists of a positively charged ion fluid and trapped, as well as free electrons. The modified Zakharov-Kuznetsov equation is derived by the usual reductive perturbation technique in a three-dimensional system. A nonlinear double layer solution is presented. Furthermore using Sagdeev’s pseudopotential technique, nonlinear double layer solution, which is associated with a set of nonlinear eigenvalue conditions, is also presented. These solutions are the analytic extensions of the monotonic double layers and solitary holes. The effects of physical parameters of nonlinear double layers are discussed. In particle simulations of a current driven system, physical relations among the obliqueness, the propagating velocity, the inverse scale length, and the maximum potential are investigated. The maximum potential and the width of the NDL decreases as the degree of the angle increases. In a chosen field, a decrease of potential width (or maximum potential) is clearly shown in the case of less than 10°. Variation of propagating velocity is clearly shown in the range of 10°–16°. Particle simulations are performed with an axially bounded electrostatic particle-in-cell code XPDP1, which is a workstation version of a one-dimensional bounded plasma code PDW1 [J. Comput. Phys. 80, 253 (1989)]. These particle simulation results are in good agreement with the qualitative theoretical results.

A theoretical investigation is carried out for understanding the properties of obliquely propagating monotonic double layers in a magneto-plasma. By using Sagdeev’s pseudopotential method, we have found an obliquely propagating double layer solution and a relation between the amplitude, the inverse scale length and the obliqueness effects. Furthermore, we show that the monotonic double layers are nonlinear extensions of the solitary holes having negative trapping parameter in magnetized plasma.