A unified theory of nonlinear Langmuir waves, ion-acoustic solitons, and double layers

Steady-state, nonlinear potential solutions in a two-fluid plasma are formulated in terms of an integral equation that expresses the conservation of total pressure. By appropriately specifying the conservation constants and boundary conditions of the effective potential function, the integral curves yield, respectively, three types of solutions: nonlinear Langmuir waves, ion-acoustic solitons, and double layers. The similarities and differences of the existence conditions for these nonlinear potential structures are discussed