Numerical simulation of the collective regime of the evolution of a low-threshold optical breakdown in an aerosol medium

Abstract

Investigations of aerosol optical breakdown have recently been extensively developed, inasmuch as it is precisely the disperse fraction which determines the threshold of the onset of a plasma region and its main characteristics in the case of propagation of beams in the visible and infrared bands under real conditions. Defining breakdown as a plasma-formation effect in an optical field, it is necessary to separate two essentially different forms of this phenomenon. The first is characterized by relatively high threshold (in this case the aerosol particles assume only the role of a "primer") while the second, with lower threshold, calls for the presence of aerosol particles (or of their vapors) in the focal region of the laser during all the stages of its evolution. Naturally, the minimum breakdown threshold in an ensemble of aerosol particles would take place in the case when during the time not exceeding the duration of the laser pulse one can ensure effective interaction of the plasma formation processes between the individual aerosol particles. A similar collective regime of lowthreshold optical breakdown was first predicted in [i], and a number of its essential features were investigated in [2-4].