Expansion dynamics and equilibrium conditions in a laser ablation plume of lithium: Modeling and experiment
Expansion dynamics and equilibrium conditions in a laser ablation plume of lithium: Modeling and experiment
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DOI：
10.1063/1.1840099
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发表时间：
2005-03-15
影响因子：
3.2
通讯作者：
Mosnier, JP
中科院分区：
文献类型：
--
作者：
Stapleton, MW;McKiernan, AP;Mosnier, JP
本文分别采用等温和等熵自相似解析解和稳态碰撞辐射方程，建立了激光烧蚀锂羽流的气体动力学和原子动力学数值模型。对不同激光波长（266-1064 nm）、能量密度（2-6.5 J cm（-2））和光斑尺寸（50-1000 μ m）的羽流膨胀动力学进行了超快成像测量，为模型提供了输入参数，从而研究了激光光斑尺寸、波长和能量密度对羽流膨胀动力学和原子动力学的影响。目标反冲压力，这显然会影响羽流动力学，包括在模型中。从等离子体对激光的吸收角度讨论了激光波长和光斑尺寸对羽流动力学的影响。一个从等温等熵行为的斑点尺寸大于50 μ m的过渡是清楚地证明。平衡条件被发现只存在高达300 ns后的羽流创建，而完整的局部热力学平衡被发现局限于非常早期的部分膨胀。(C)2005年美国物理学会。
The gas dynamics and atomic kinetics of a laser ablation plume of lithium, expanding adiabatically in vacuum, are included in a numerical model, using isothermal and isentropic self-similar analytical solutions and steady-state collisional radiative equations, respectively. Measurements of plume expansion dynamics using ultrafast imaging for various laser wavelengths (266-1064 nm), fluences (2-6.5 J cm(-2)), and spot sizes (50-1000 mu m) are performed to provide input parameters for the model and, thereby, study the influence of laser spot size, wavelength, and fluence, respectively, on both the plume expansion dynamics and atomic kinetics. Target recoil pressure, which clearly affects plume dynamics, is included in the model. The effects of laser wavelength and spot size on plume dynamics are discussed in terms of plasma absorption of laser light. A transition from isothermal to isentropic behavior for spot sizes greater than 50 mu m is clearly evidenced. Equilibrium conditions are found to exist only up to 300 ns after the plume creation, while complete local thermodynamic equilibrium is found to be confined to the very early parts of the expansion. (C) 2005 American Institute of Physics.