Simulation of the thermionic emission during ultrashort pulse laser ablation of metals

Abstract

The characteristics of thermionic emission of metal films during ultrashort pulse laser ablation are investigated by numerical simulation. The two-temperature model is used to calculate the electron and lattice temperatures while thermionic emission is incorporated into the model as a surface phenomenon. The Richardson-Dushman equation is employed to estimate the rate of thermionic electron emission. The influence of laser irradiance and the film thickness on the emission rate is examined. The change of quantum efficiency is predicted and compared with reported experimental data. The evolution of electron and lattice temperatures and the variation of relaxation time are also investigated in accordance with thermionic emission. © 2007 IOP Publishing Ltd.