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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。
Pulsed laser irradiation of solid targets, the instantaneous target surface can be irradiated to form a high temperature and high pressure plasma layer. The plasma is sprayed at high velocity to impose a very high pressure on the target surface, resulting in a series of compressional waves propagating into the target. As the laser continues to irradiate, one after another incoming compressional waves within the target form a steep shock wave. When the laser intensity remains constant, the ablation pressure exerted on the target surface remains the same, so the shock wave front pressure in the target will maintain a stable phase. In the latter part of the laser and the target role, as the laser power density decreases, the surface ablation pressure decreases, which will be a series of sparse waves into the target, due to the sparse wave in local sound velocity and wave velocity after the sum of particle velocity Spread, then after a period of time, the sparse wave catches and superimposes the shock wave, which results in a reduction of the shock wave front pressure. Laser shock in the target also experienced the strengthening, sustaining and decaying three stages. In this paper, the fluid dynamics model is used to describe the generation, enhancement, maintenance and attenuation of shock waves in the pulsed laser irradiation. The spatio-temporal relationships between the shock wave peak pressure, the shock velocity and the shock wave are given .