Characteristics of some nonlinear coherent wave structures in a collisionless weakly relativistic plasma with nonthermal electrons

In some recent on board space observations, it has been studied that high streaming ions play a major role on the physical mechanism for nonlinear wave structures. We have investigated here ion-acoustic solitons in a plasma with nonthermal electrons and weakly relativistic ions. Such plasmas occur in plasma sheet boundary layer of earth's magnetosphere, Van-Allen belts. We have set up and solved KdV equation in a stationary frame to obtain the expression for the peak soliton amplitude and width. These quantities are significantly influenced by the relativistic effect, the nonthermal parameters and ratio of ion to electron temperatures. It is observed that for specific range of nonthermal parameter values, we observe compressive solitons and above which the rarefactive solitons are observed. The nonthermal parameter also affects the double layers.