CONTRIBUTION OF HIGHER-ORDER NONLINEARITY TO NONLINEAR ION-ACOUSTIC-WAVES IN A WEAKLY RELATIVISTIC WARM PLASMA .1. ISOTHERMAL CASE

The contribution of higher-order nonlinearity to nonlinear ion-acoustic waves in a weakly relativistic plasma consisting of warm ion-fluid and hot isothermal electrons is investigated using reductive perturbation theory. A Korteweg-de Vries-type equation, with temperature- and relativistic-parameter-dependent coefficients is obtained. The renormalization method is applied to the equations obtained from the different orders of perturbation theory to obtain a stationary solution. Relativistic cold and non-relativistic warm plasma limits are considered in order to make comparisons with previous results.