Abstract Plasma is commonly existing in pulsed laser drilling and it has an important impact on drilling results. The effects include plasma absorption and defocusing effect caused by plasma. This paper studied the influence of plasma on laser drilling by a combination method of numerical simulation and experiment. Based on the combination of computational fluid dynamics (CFD), fluid-solid coupling theory, double-temperature model, C ++ programming and OpenFOAM simulation, this paper established and added the defocusing effect and energy absorption of plasma as sub-modules. Finally, this paper conducted a series of laser drilling experiments with different parameters such as repetition rate, laser power and pulse number. Comparison of the results of simulations and experiments were conducted to verify the accuracy of the improved model. The comparison results proved that plasma play a significant role in pulsed laser drilling and the accuracy of the modificated model is very high. There is another conclusion that the influence of defocusing effect on laser drilling is greater than that of energy absorption.

中文翻译：

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皮秒激光钻孔中等离子体的散焦效应和能量吸收

摘要 脉冲激光钻孔中普遍存在等离子体，它对钻孔结果有重要影响。影响包括等离子体吸收和由等离子体引起的散焦效应。本文采用数值模拟和实验相结合的方法研究了等离子体对激光钻孔的影响。本文在计算流体动力学（CFD）、流固耦合理论、双温模型、C++编程和OpenFOAM仿真相结合的基础上，建立并加入了等离子体散焦效应和能量吸收等子模块。最后，本文对重复率、激光功率和脉冲数等不同参数进行了一系列激光钻孔实验。通过仿真和实验结果的对比，验证了改进模型的准确性。对比结果证明，等离子体在脉冲激光钻孔中发挥着重要作用，修正模型的精度非常高。还有一个结论是散焦效应对激光钻孔的影响大于能量吸收。