New insights into the formation of nonlinear space charge structures in various plasmas

In this review, a brief introduction to some general properties of nonlinea r space charge structures and their connection with the current voltage cha racteristic of a plasma system is given. Some new phenomena in a Q-machine plasma and a DP-machine plasma are presented and tentative models are discu ssed in order to emphasise the role of electron impact excitation and ionis ation interactions for the formation of nonlinear space charge structures e ven in so-called collisionless plasmas.