摘要
基于椭球模型,考虑到脉冲激光的能量传播特性,提出了聚焦区域的光强的表达式,分析了液体中光击穿的机制,对于多光子电离诱导的雪崩电离,简化了等离子体中自由电子密度演化过程的速率方程,修正了电子扩散速率和雪崩电离速率,得到了雪崩电离产生的自由电子密度的解析表达式,并利用雪崩电离产生的自由电子密度的解析表达式,得到了长、短脉宽的雪崩电离击穿光强阈值的解析表达式,进而讨论了长、短脉宽激光情况下,脉冲宽度、初始电子密度、扩散速率以及复合速率对击穿阈值的影响。此外,通过该解析表达式得到的光强阈值与实验结果符合较好。
Bases on the ellipsoidal model,the expression of laser intensity in the focal region was proposed by considering the characteristics of energy propagation,and the mechanism of the optical breakdown in liquids was analyzed.For the cascade ionization induced by multiphoton ionization,the free electron density rate equation was simplified and the rates of electron diffusion and cascade ionization were modified to get the analytical expression of free electron density caused by cascade ionization. And then get the analytical expressions of the optical breakdown threshold under the condition of the long-pulse and short-pulse lasers and probes into the effects of the breakdown threshold on the pulse width,the initial electron density,the diffusion rate and the cascade ionization rate. Moreover,the results calculated by the analytical expressions fit the experiment results well.
出处
《激光杂志》
北大核心
2017年第8期48-51,共4页
Laser Journal
基金
国家自然科学基金资助项目(11074159
11374199)
关键词
光击穿
椭球模型
自由电子密度
阈值
optical breakdown
ellipsoid model
free electron density
threshold
