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发展了一个激光与靶蒸气相互作用的简化物理模型,应用这个模型对激光维持爆震波(Laser Supported Detonation Waves,即LSDWs)的点火机理、传播规律作了数值研究并取得了较好的结果。在物理模型中,假定电子和离子组分之间处于非局部热动平衡,采用欧拉坐标中的电子和离子双温流体力学方程组描述金属靶蒸气的运动;采用平衡电离假定,求解Sa-ha方程;激光吸收机理为逆轫制过程;电子和离子之间通过Coulomb碰撞、电子和中性原子之间通过弹性势散射交换能量;分别考虑电子和离子热传导。计算得到的LSD波阈值与实验结果合理地符合,并且LSD波阈值与激光脉宽的关系表现出典型的幂规律I_(TH)∝τ_P~(-1/2)。此外,还得到了一些关于LSD波屏蔽效应的有益结果,在LSD波充分发展的阶段,LSD波阵面的光学厚度可达5～10的量级,这表明LSD波具有很强的屏蔽作用。
A simplified physical model of interaction between laser and target vapor was developed. The ignition mechanism and propagation law of laser sustaining Detonation Waves (LSDWs) were numerically studied and good results were achieved by using this model. In the physical model, assuming that the electron and ion components are in a non-local thermodynamic equilibrium, the electron and ion dual-temperature hydrodynamic equations in Eulerian coordinates are used to describe the motion of the metal target vapor. The equilibrium ionization assumption is used to solve the Sa- ha equation; the mechanism of laser absorption is reverse slugging; the Coulomb collisions between electrons and ions exchange energy by elastic potential scattering between the electrons and the neutral atoms; the conduction of electrons and ions, respectively, is considered. The calculated LSD wave threshold is reasonably consistent with the experimental results, and the relationship between the LSD wave threshold and the laser pulse width shows a typical exponential law, I TH (TH) ατ_P -1 (-1/2). In addition, some beneficial results have been obtained on the LSD wave shielding effect. The optical thickness of the LSD wavefront can reach the order of 5-10 on the stage of fully developed LSD wave, indicating that the LSD wave has a strong shielding effect.