康普顿散射对飞秒光丝中等离子体密度时演特性的影响  

Influences of Compton Scattering to Temporal Evolution of Plasma Density in Femto-Second Light Filaments

作　　者：郝东山[1] 

机构地区：[1]郑州华信学院信息工程系,河南新郑451100

出　　处：《中国激光》2014年第5期108-112,共5页Chinese Journal of Lasers

基　　金：河南省基础与前沿技术研究项目(092300410227);河南省教育厅科学技术研究重点项目(12B520063)

摘　　要：通过康普顿散射模型、等离子体时间切片模型和数值计算方法研究了飞秒光丝中等离子体密度时演特性,提出了将康普顿散射光作为改变等离子体电子峰值密度的新机制,给出了带电粒子动力学修正方程,并进行了数值计算。研究发现散射使等离子体达到导电的时间缩短,电离区电子密度增长呈准饱和状态,电离衰退区电子密度近乎恒定,不同脉冲电离贡献率差别很小。随脉冲切片光强增强,O2电离贡献率有所下降,N2电离贡献率最终超过O2贡献率,等离子体通道内电子峰值密度增大,通道寿命延长。相同峰值强度下,长、短脉冲产生的电子密度峰值增长几乎相同,且较散射前有所减小。The influences of Compton scattering to temporal evolution of plasma density in femto-second light filaments are studied by using Compton scattering model, plasma time-section model and number computing means. A new mechanism that the electron crest density in the plasma is changed by Compton scattering is proposed. The amended dynamic equations of charged particles are given out, and the equations are computed by numerical method. The results show that the time the plasma need to be conductive is reduced by Compton scattering, the increasing of electron density in the ionization area is in quasi-saturated state, the electron densities in the ionization decreased area is almost constant, and the differences of the ionization contribution rates of different pulses are very little. The 02 ionization contribution rate decreases along with the increase of the light intensity of the pulse section and the O~ ionization contribution rate is finally overstepped by the N2 contribution rate. The electron crest density increases in plasma channel and the channel lifetime is extended as well. Under the same crest density, the increases of the electron crest density produced by the long or short pulses are almost the same, and the increases are rather smaller after scattering.

关 键 词：非线性光学 飞秒激光成丝 等离子体通道 电子峰值密度 多光子非线性康普顿散射 

分 类 号：O437.5[机械工程—光学工程]