飞秒激光诱导水光学击穿的椭球体模型

基于飞秒激光脉冲在焦点区域的成形特征和速率方程,通过对自由电子密度速率方程中电子扩散速率和雪崩速率的修正,提出了适用于飞秒激光脉冲诱导水光学击穿的椭球体(ETS)模型.采用四阶朗格-库塔(Runge-Kutta)方法对该模型进行了脉宽为100 fs和300 fs情况下的数值模似.得到了光学击穿阈值以及击穿区域内不同时刻的电子分布,并且预测了焦点区域内不同位置处自由电子随时间的变化趋势.结果表明,用ETS模型计算出的水的击穿阈值较传统模型更好地与实验结果吻合.

Ellipsoidal Time and Space Model for Femtosecond Laser-Induced Optical Breakdown in Water

Based on the shaping characteristic of femtosecond in the focal region and the free electron density rate equation,through modifying the electron diffusion rate and cascade ionization rate,the ellipsoidal time and space (ETS)model for femtosecond laser-induced optical breakdown in water was given.Theoretical breakdown thresholds calculated by ETS model with a Runge-Kutta method were presented under the condition of pulse durations of 100 fs and 300 fs.The optical breakdown thresholds and the electron distribution within the breakdown region at different times were given,and the change of free electrons with time at fixed positions within the region was predicted.Results show that the breakdown threshold of water induced by femtosecond laser using the ETS model is better agreement with experimental result than the classical models.