A new model of pulsed laser ablation and plasma shielding

A new theoretical model of pulsed laser ablation has been developed, which studies the characteristics of laser-plasma interaction and the effect of plasma shielding in the ablation process. Two different absorption processes are considered, namely inverse bremsstrahlung and photoionization of excited species, also plasma radiation is included. The model is used to simulate 25 ns square pulsed laser irradiation on YBa2Cu3O7 targets. The evolution of the plasma length and the transmitted intensity are performed, and the variation of ablation depth per pulse with energy density at three most common excimer wavelengths (193, 248 and 308 nm) are simulated too. Moreover, we obtain the dependence of ablation depth on the number of laser pulses at 248 nm. Under the same experimental conditions, our numerical results are more in agreement with the experimental results, which confirms that plasma shielding plays a relevant role in the ablation process. (c) 2005 Elsevier B.V. All rights reserved.