Two-Zone Model of Laser-Induced Plasma

Abstract

A plasma modeling algorithm using a two-zone light source approximation has been developed and coupled with the NLopt library for multiparametric optimization. An abstraction layer was created to streamline the initialization of both libraries in a single step, to calculate a loss function of the specified type, and to convey its value to the optimization algorithm. The proper functioning of these combined algorithms was confirmed with model data, demonstrating convergence to the plasma parameters that were used to generate a test synthetic spectrum. The CRS2-LM algorithm enables the fastest convergence to the original spectrum; hence, it has been utilized for the approximation of experimental spectra. It has been demonstrated that the application of a two-zone model provides an accurate description of both ionic and atomic lines, including those that are self-reversed during the evaporation of aluminum alloys. Furthermore, “blind” optimization methods for the loss function are effective for determining temperature and electron density in laser-induced plasma from its spectra.