Formation and Interaction of Ion-Acoustic Solitary Waves in a Collisionless Warm Plasma

The formation and interaction of solitary waves in a warm-ion, hot isothermal electron plasma have been studied with the Vlasov equation for ions and Boltzmann distribution for electrons. An arbitrary initial potential pulse having a width smaller (or larger) than that of a solitary wave decomposes into one (or several) solitary wave(s) with (or without) ion-acoustic oscillations behind. In the interaction of two solitary waves, it has been found that: (1) If the initial amplitude ratio is not too large, the two waves exchange their amplitudes and bounce apart; (2) if the initial amplitude ratio is large, the larger wave first absorbs the smaller, subsequently re-emits it behind. A steady-state solitary wave solution for the ion fluid equations with a scalar pressure and Boltzmann electrons presents a smaller width and a larger velocity than the solution of the Korteweg-de Vries equation with the same amplitude. The limiting Mach number is smaller than Sagdeev's value.