Experiments on the propagation of an ion-acoustic soliton into a region of inhomogeneous plasma density are described. It is found that the local amplitude and velocity decrease and the width increases as the soliton propagates into a region of lower density. The results are in good agreement with a model based on the KdV equation and with the recent study of Kuehl and Imen [Phys. Fluids 28, 2375 (1985)].

Experiments on the expansion of a plasma into the wake region behind an object inserted in a flowing plasma are described. The dominant expansion mechanism that fills in the wake is determined to be a self-similar expansion. Accelerated ions with a velocity greater than the local ion-acoustic velocity are detected ahead of the self-similar expansion front. In a plasma with two species, two groups of accelerated ions are detected.

The propagation of an ion-acoustic soliton from a quiescent plasma region into a localized non-quiescent region (An n/sol,ion z An ninobrc) is experimentally examined. Sekeral of the soliton properties are preserved although the soliton undergoes an enhanced damping as it propagates in the noisy plasma.

Experiments on the propagation of an ion-acoustic soliton from an isotropic plasma into a region containing a weak mirror magnetic field are described. An anomalous focusing of the soliton is detected. The magnetic field also allows us to separately observe reflected ions from the soliton and the ions involved in the excitation of the soliton.

The two-dimensional evolution of an ion-acoustic soliton from a grid with regular or random perturbations in the direction transverse to the direction of the soliton propagation is experimentally examined. The soliton initially follows the contour of the exciting grid but evolves into a planar structure. These experimental results are compared with a model based on the higher dimensional Kadomtsev–Petviashvili equation. Both the theoretical and numerical predictions agree with the experiment.