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

The excitation, propagation, and interaction of planar negative-potential s olitary waves in a plasma containing positive ions, negative ions, and elec trons (i.e., an electronegative plasma) are studied using a hybrid simulati on with kinetic, particle ions, and Boltzmann electrons. Solitary waves are launched into the plasma when the potential on an initially unbiased elect rode is stepped downward. They then propagate self-consistently through the ambient plasma. Results are shown for excitation and propagation as well a s for overtaking collisions. During overtaking collisions, the solitons pre serve their shape and speed, though they are not necessarily described by t he Korteweg-deVries theory. These solitons may provide a useful diagnostic of the negative ion concentration in electronegative plasmas. (C) 1999 Amer ican Institute of Physics. [S0021-8979(99)01019-1].