Excitation and propagation of negative-potential solitons in an electronegative plasma

The excitation, propagation, and interaction of planar negative-potential solitary waves in a plasma containing positive ions, negative ions, and electrons (i.e., an electronegative plasma) are studied using a hybrid simulation with kinetic, particle ions, and Boltzmann electrons. Solitary waves are launched into the plasma when the potential on an initially unbiased electrode is stepped downward. They then propagate self-consistently through the ambient plasma. Results are shown for excitation and propagation as well as for overtaking collisions. During overtaking collisions, the solitons preserve their shape and speed, though they are not necessarily described by the Korteweg-deVries theory. These solitons may provide a useful diagnostic of the negative ion concentration in electronegative plasmas.