Instabilities and structures in optical and microwave breakdown processes

The results of investigations on the nonlinear dynamics of the field and pl asma in the gas breakdown processes produced by a high-intensity laser and microwave pulses are presented. The ionization nonlinearity dominates under the conditions considered and results in a number of important effects of a new type, which are absent for other nonlinear mechanisms. The scope of e ffects focused on here is associated with the phenomena of mutual concentra tion (joint localization) of the field and field-created plasma. They, in p articular, manifest themselves as fast small-scale instabilities at the gas breakdown stage, the generation of high local peaks in the field amplitude , electron density and temperature, and the creation of long-lived states w ith a high level of Langmuir turbulence. (C) 2001 American Institute of Phy sics.