Instabilities and structures in optical and microwave breakdown processes

The results of investigations on the nonlinear dynamics of the field and plasma 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 effects focused on here is associated with the phenomena of mutual concentration (joint localization) of the field and field-created plasma. They, in particular, 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 with a high level of Langmuir turbulence.