Collaborative Research: A Novel Dual-Pulse Laser Ablation and Plasma Amplification (LAPA) Process for Drilling Non-straight Holes with Arbitrarily Varying Diameters

这笔资金用于研究一种新的双脉冲激光烧蚀和等离子体放大(LAPA)工艺，用于钻孔直径随深度任意变化的非直微孔。许多重要的应用越来越需要这种微孔。然而，他们的精确和高效钻探仍然是一个巨大的挑战。研究的目的是(1)验证在LAPA中，用第二个皮秒激光脉冲放大纳秒激光产生的等离子体可以通过等离子体-侧壁相互作用实现可控和精确的微孔侧壁材料去除的假设，(2)了解与LAPA相关的基本物理。具体研究任务包括：(1)建立LAPA实验装置。(2)建立了LAPA的理论模型，可以模拟激光烧蚀和等离子体产生以及激光-等离子体-侧壁相互作用。(3)测量等离子体性质以验证模型，了解LAPA的基本物理过程。(4)在验证模型的指导下进行可行性试验研究。泵浦探测、快速成像和发射光谱技术将被用于等离子体性质的测量。将求解非线性薛定谔方程和双温流体动力学方程，并与分子动力学/蒙特卡罗模块耦合，模拟激光-等离子体-孔壁相互作用。LAPA是国际标准化组织提出的一种新型制造工艺。它的基本物理过程是皮秒激光脉冲、等离子体(由前一纳秒激光脉冲产生)和微孔侧壁之间的相互作用，这方面的研究很少，了解也很少。这个项目将通过将多尺度建模与综合实验相结合，为这种相互作用提供一个很好的、基本的理解。研究工作将为LAPA的实际应用奠定坚实的科学基础。它还将提高我们对一般意义上的激光-等离子体-材料相互作用的理解，这可能会改进其他现有的或启发新的激光和/或等离子体辅助制造工艺。

This grant provides funding to study a novel dual-pulse laser ablation and plasma amplification (LAPA) process for drilling non-straight microholes with diameters varying arbitrarily with depth. Such kinds of microholes have been increasingly needed by many important applications. However, their precise and efficient drilling still remains a big challenge. The research objectives are to (1) test the hypothesis that in LAPA the amplification of nanosecond-laser-generated plasma by a second picosecond laser pulse can realize controlled and precise material removal from a microhole sidewall through plasma-sidewall interactions and (2) understand the fundamental physics associated with LAPA. The specific research tasks include: (1) Establish an experimental set-up for LAPA. (2) Establish theoretical models for LAPA, which can simulate laser ablation and plasma generation, and laser-plasma-sidewall interactions. (3) Measure the plasma properties to verify the models and understand the fundamental physical processes in LAPA. (4) Perform a feasibility experimental study under the guidance of the verified models. The pump-probe, fast imaging and emission spectroscopy techniques will be used in plasma property measurements. The nonlinear Schrödinger equation and two-temperature hydrodynamic equations will be solved and coupled with a molecular dynamics/Monte Carlo module in modeling the laser-plasma-hole sidewall interactions during LAPA. LAPA is a novel manufacturing process proposed by the PI. Its essential physical process is the interaction among picosecond laser pulse, plasma (generated by a prior nanosecond laser pulse), and microhole sidewall, which has been rarely studied and is still poorly understood. This project will provide a good, fundamental understanding of this interaction by combining multiscale modeling with comprehensive experiments. The research work will build a solid scientific foundation crucial for LAPA's practical applications. It will also improve our understanding of laser-plasma-material interactions in the general sense, which may improve other existing or inspire new laser and/or plasma-assisted manufacturing processes.