This paper numerically simulates the process of ablation of an aluminum target by an intense femtosecond laser with a fluence of 40 J/cm2 based on the two-temperature equation, and obtains the evolution of the free el...This paper numerically simulates the process of ablation of an aluminum target by an intense femtosecond laser with a fluence of 40 J/cm2 based on the two-temperature equation, and obtains the evolution of the free electron temperature and lattice temperature over a large temporal and depth range, for the first time. By investigating the temporal evolution curves of the free electron temperature and lattice temperature at three representative depths of 0, 100 nm and 500 nm, it reveals different characteristics and mechanisms of the free electron temperature evolution at different depths. The results show that, in the intense femtosecond laser ablation of aluminum, the material ablation is mainly induced by the thermal conduction of free electrons, instead of the direct absorption of the laser energy; in addition, the thermal conduction of free electrons and the coupling effect between electrons and lattice will induce the temperature of free electrons deep inside the target to experience a process from increase to decrease and finally to increase again.展开更多
采用结合双温模型的分子动力学的方法,数值模拟了脉宽100 fs,能量密度为40~200 m J/cm^2的飞秒激光与CuZr非晶合金的相互作用过程。低能量密度下,靶材的烧蚀机制主要表现为机械破碎;高能量密度下,热机械蚀除和相爆炸共同存在于靶材的烧...采用结合双温模型的分子动力学的方法,数值模拟了脉宽100 fs,能量密度为40~200 m J/cm^2的飞秒激光与CuZr非晶合金的相互作用过程。低能量密度下,靶材的烧蚀机制主要表现为机械破碎;高能量密度下,热机械蚀除和相爆炸共同存在于靶材的烧蚀过程,随着能量密度的增加,相爆炸成为主要蚀除机制。利用径向分布函数分析了CuZr非晶合金结构的无序性,分析结果表明,激光能量密度由80 m J/cm^2增加到120 m J/cm^2时,飞秒激光与靶材相互作用过程中,材料内部的原子保持着无序状态,材料未发生明显晶化。展开更多
Two dimensional three temperatures energy equation is a kind of very impor-tant partial differential equation. In general, we discrete such equation with full implicit nine points stencil on Lagrange structured grid a...Two dimensional three temperatures energy equation is a kind of very impor-tant partial differential equation. In general, we discrete such equation with full implicit nine points stencil on Lagrange structured grid and generate a non-linear sparse algebraic equation including nine diagonal lines. This paper will discuss the iterative solver for such non-linear equations. We linearize the equations by fixing the coefficient matrix, and iteratively solve the linearized algebraic equation with Krylov subspace iterative method. We have applied the iterative method presented in this paper to the code Lared-Ⅰ for numerical simulation of two dimensional threetemperatures radial fluid dynamics, and have obtained efficient results.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 10904079 and 60838001)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20090031120041)the Natural Science Foundation of Tianjin (Grant No. 10JCYBJC01300)
文摘This paper numerically simulates the process of ablation of an aluminum target by an intense femtosecond laser with a fluence of 40 J/cm2 based on the two-temperature equation, and obtains the evolution of the free electron temperature and lattice temperature over a large temporal and depth range, for the first time. By investigating the temporal evolution curves of the free electron temperature and lattice temperature at three representative depths of 0, 100 nm and 500 nm, it reveals different characteristics and mechanisms of the free electron temperature evolution at different depths. The results show that, in the intense femtosecond laser ablation of aluminum, the material ablation is mainly induced by the thermal conduction of free electrons, instead of the direct absorption of the laser energy; in addition, the thermal conduction of free electrons and the coupling effect between electrons and lattice will induce the temperature of free electrons deep inside the target to experience a process from increase to decrease and finally to increase again.
文摘采用结合双温模型的分子动力学的方法,数值模拟了脉宽100 fs,能量密度为40~200 m J/cm^2的飞秒激光与CuZr非晶合金的相互作用过程。低能量密度下,靶材的烧蚀机制主要表现为机械破碎;高能量密度下,热机械蚀除和相爆炸共同存在于靶材的烧蚀过程,随着能量密度的增加,相爆炸成为主要蚀除机制。利用径向分布函数分析了CuZr非晶合金结构的无序性,分析结果表明,激光能量密度由80 m J/cm^2增加到120 m J/cm^2时,飞秒激光与靶材相互作用过程中,材料内部的原子保持着无序状态,材料未发生明显晶化。
文摘Two dimensional three temperatures energy equation is a kind of very impor-tant partial differential equation. In general, we discrete such equation with full implicit nine points stencil on Lagrange structured grid and generate a non-linear sparse algebraic equation including nine diagonal lines. This paper will discuss the iterative solver for such non-linear equations. We linearize the equations by fixing the coefficient matrix, and iteratively solve the linearized algebraic equation with Krylov subspace iterative method. We have applied the iterative method presented in this paper to the code Lared-Ⅰ for numerical simulation of two dimensional threetemperatures radial fluid dynamics, and have obtained efficient results.
