摘要
脉冲强激光辐照固体靶材时 ,瞬间即可在靶材辐照面形成一个高温高压的等离子体层。该等离子体向外高速喷射 ,从而施于靶面一个压力极高的冲击加载 ,导致一系列向靶内传播的压缩波。随着激光的持续辐照 ,陆续传入靶内的压缩波会形成一个阵面陡峭的激波。当激光强度保持恒定时 ,施于靶面的烧蚀压力亦保持不变 ,因而此时靶内的激波阵面压力会维持一个平稳阶段。在激光与靶材作用的后期 ,由于激光功率密度减小 ,表面烧蚀压降低 ,因而将一系列稀疏波传入靶内 ,由于稀疏波以当地声速和波阵面后粒子声速之和的速度传播 ,则经过一段时间之后 ,稀疏波便赶上激波并与之迭加 ,其结果使得激波波阵面压力降低。激光激波在靶材中同样经历着增强、持续和衰减三个阶段。文中采用流体动力学模型 ,解析地描述了脉冲强激光辐照靶材时 ,激波的产生及增强、维持和衰减规律 ,给出了激波峰值压力、激波速度、激波波形的时空关系。
As a powerful pulsed laser irradiate a solid material, the plasmas layer of high\|temperature and high\|pressure would be formed in the incident surface of target instantaneously. The plasmas ejects in a high speed, and gives impulsion loading to the target surface which results in a series of compress wave propagation into target. This would produce shock wave owing to splice of compress wave. The evolution of shock wave can separate into three stages as (1) the forming stage “pressure increases”, (2) the stage of “maximum pressure”, (3) the decay stage “pressure decreases”. An analytical method for study creation and decay of laser induced shock wave in the target are presented on the basis of one\|dimensional hydrodynamic model. The ablation pressure is used as boundary condition. The method permits the calculation of the three stages of shock wave evolution, and gives the temporal and spatial relationship of peak pressure, velocity, and profile of shock wave.
出处
《红外与激光工程》
EI
CSCD
2000年第2期41-45,50,共6页
Infrared and Laser Engineering
关键词
烧蚀压力
激光激波
脉冲激光
靶材
Laser effects\ \ Ablation pressure\ \ Shock wave induced by laser
