<title>Modeling of a high-energy laser pulse focused within an aerosol spray</title>

Abstract

A computer program is being developed for the theoretical analysis of the propagation of a laser pulse optically focused within an aerosol spray. The computer program can be applied, for example, to analyze laser ignition arrangements where a focused laser pulse would be used to ignite a liquid aerosol fuel spray. Laser light scattering and absorption of the individual aerosol droplets are evaluated using electromagnetic Lorenz-Mie theory. Initially, beam propagation is being modeled using a simple modified paraxial theory. Arbitrary input parameters to the computer program describing the optical/laser/aerosol spray arrangement include the liquid volume fraction, average droplet size, droplet size distribution, laser wavelength, laser pulse energy, laser pulse duration, lens focal length, beam diameter incident on the lens, and the choice of aerosol liquid and surrounding gaseous medium (through arbitrary inputted values of the thermodynamic and optical properties of the aerosol liquid and the gaseous medium). The output of the computer program includes, as a function of spatial position along the laser propagation axis within the spray, the laser pulse intensity and energy, the overall volumetric absorption of laser energy by the aerosol liquid and by the gaseous medium, and the overall average temperature rise of the aerosol liquid and of the gaseous medium.