2 WAVE COLLAPSES AND A STRANGE SOLITON IN CURRENT-CARRYING PLASMAS

A current driven plasma is analyzed in the two-fluid approach. A Lagra ngian treatment of the charge neutral system results in a nonlinear sc alar wave equation, which exhibits two different singular wave solutio ns. One wave collapse is associated with a density. excavation, the ot her with a density compression. The latter represents the scenario of wave breaking and survives under charge separation. A new soliton solu tion is found just above threshold of linear instability of the charge nonneutral system in case of hot electrons. It is reminiscent of an i on acoustic KdV-soliton but differs from it in several respects such a s in the propagation speed, in the strength and polarity of the electr ostatic potential and in the spatial width, It is a finite ion tempera ture effect and disappears in the cold ion limit T-i --> 0.