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为研究532nm和1064nm两种典型激光波长对纳秒脉冲激光烧蚀铝靶冲量耦合特性的影响,在建立的热传导模型和羽流膨胀流体动力学模型基础上,加入了在激光烧蚀过程中靶材吸收系数、热导率和反射率等光学和热物理参数的变化,考虑了形成的等离子体羽流对入射激光的屏蔽作用因素影响,从而建立了一个复杂的一维纳秒激光烧蚀铝靶冲量耦合物理模型。通过计算,获得了两种激光波长辐照下,烧蚀过程中烧蚀参数和物理参数的变化,分析等离子体羽流对入射激光的屏蔽效应,进一步分析得到对冲量耦合特性的影响。结果表明:短波长激光不仅有利于激光与靶材的能量耦合,同时,短波长激光辐照下形成的等离子体羽流对短波长入射激光吸收率也较低,有利于提高靶的冲量耦合;在等离子体形成初期,即等离子体吸收率较低时,分别达到两种激光波长辐照下的最优冲量耦合。
In order to study the influence of two typical laser wavelengths, 532 nm and 1064 nm, on the impulse coupling characteristics of nanosecond-pulsed laser ablation aluminum target, based on the established thermal conductivity model and plume expansion hydrodynamic model, The change of optical and thermal physical parameters, such as material absorption coefficient, thermal conductivity and reflectivity, were considered in consideration of the influence of the plasma-forming plume on the shielding effect of the incident laser. Thus, a complex one-dimensional nanosecond laser ablated aluminum Target Impulse Coupling Physical Model. The changes of ablation parameters and physical parameters during the ablation process under two laser wavelength radiations were obtained by calculation. The shielding effect of the plasma plume on the incident laser was analyzed. The influence of the impulse coupling characteristics was further analyzed. The results show that the short wavelength laser is not only beneficial to the energy coupling between the laser and the target, but also the plasma plume formed by the short wavelength laser irradiation has a low absorption rate of the short wavelength incident laser, which is beneficial to increase the impulse coupling of the target. In the early stage of plasma formation, that is, when the plasma absorption rate is low, the optimal impulse coupling at two laser wavelength irradiations is achieved respectively.