High Energy and High Intensity Laser Effects on Aerosols: Changes in Droplet Morphology, Surrounding Temperature, and Vapor Concentration

摘要

Nonlinear optical interactions in a droplet occur at remarkably low input intensity levels because the droplets act as a lens to concentrate the input radiation at a location just within the shadow face and as an optical cavity to provide feedback for the internally generated radiation. LIB within the droplet occurs when the rising portion of the input laser pulse causes multiphoton ionization which is followed by cascade multiplication. The resultant plasma within the droplet transforms a nominally transparent droplet into an absorbing droplet, and the remaining portion of the input laser pulse heats the droplet. Multiple scattering calculations and measurements were made from two closely spaced fibers which served as a prototype of densely packed aerosols. The comparison between the exact calculation for two fibers and the experimental results from the fiber-mirror configuration was excellent and provided new insight into the multiple scattering from closely spaced aerosols.