Recurrence of ion waves and soliton-like interaction

Nonlinear interaction of ion waves has been studied in a slightly unstable plasma in which the waves could propagate without dissipation over a long distance. Recurrence of waves during propagation is observed under two different initial conditions, i.e. purely sinusoidal or consisting of the fundamental and the second harmonic. In the latter case, the recurrence has the appearance of a soliton, reversible scattering successively taking place during continuous wave propagation. The recurrence length which mainly depends on the dispersive properties of the plasma, is in good agreement with theory based on an extension of the Korteweg-de Vries equation which takes into account the effect of finite ion temperature.