Collaborative Research: Modeling and Analysis of High Energy Ultrashort Laser-Induced Plasmas and Shockwave

[853528]本项目的目标是通过建模和实验来了解和控制高能、超短激光与固体相互作用过程中等离子体和冲击波的形成。特别是，早期等离子体发生在固体表面附近，被高能，超短激光束照射将被研究。目标是控制激波和等离子体的特性，以便它们可以被利用来创造新的结果，如灯丝效应，即自聚焦和等离子体去聚焦之间的动态平衡产生的等离子体颤振的形成。该研究将有助于开发与超短、高功率激光器相关的激光-物质相互作用的合适建模技术。知识价值。将建立一个多尺度混合模型来研究等离子体的早期形成及其与激光束和目标表面的相互作用。对于早期等离子体的形成，将建立一个结合分子动力学和蒙特卡罗模型（MD/MC）来计算中性粒子、电子、离子、光子和声子的动力学，同时考虑这些粒子之间的相互作用。由于计算复杂性限制了MD/MC组合的时空计算域的大小，因此MD/MC将与目标材料深处的有限差分模型相结合，并与目标表面以上区域的流体动力学方程相结合，以模拟等离子体/环境空气区域。这个组合模型将揭示早期等离子体形成的详细信息，以及它与激光束和目标表面的相互作用。在配套的实验研究中，将利用干涉图和阴影图技术对激光产生的等离子体和不同延迟时间的冲击波进行更全面的测量和观察。实验结果将用于模型的验证。更广泛的影响。高能、超短激光器的应用范围从薄膜的脉冲激光制造到激光微纳米制造。提高对高能超短激光与材料相互作用的理解可以显著扩展这些器件的潜在应用。这项研究将产生与未来开发适合特定应用的激光器有关的信息。研究结果将在面向工业界和学术界的会议上以及在一个专门的网站上广泛传播。一些本科生将通过普渡大学工程学院管理的暑期本科生研究奖学金（SURF）计划以及本科生独立项目参与其中。将通过现有的项目，如女性工程项目（WIEP）和少数民族工程项目（MEP），来争取代表性不足的学生的参与。该研究将被纳入本科制造课程“制造过程的原理与实践”。在伊利诺伊理工学院（IIT），这些新发现将被纳入一门名为“先进制造工程”的课程。本科生和少数民族研究生将通过本科生研究奖学金计划和印度理工学院的专题课程参与其中。基于该项目的动画演示套件将与芝加哥公立学校学生科学博览会共享，以吸引更多的学生（特别是少数民族学生）参与科学和工程。

0853528WuThe goal of this project is to develop an understanding of, and ability to control plasma and shock wave formation during high energy, ultrashort laser-solid interaction via modeling and experimentation. In particular, the early plasma that occurs near a solid surface that is irradiated by high energy, ultrashort laser beams will be investigated. A goal is to control the shock wave and plasma properties so that they may be exploited to create novel results such as filament effects, i.e., formation of a plasma chatter that results from the dynamic balance between self-focusing and plasma de-focusing. The research will enable development of a suitable modeling technique for laser-matter interaction that is associated with the use of ultrashort, high power lasers.Intellectual Merit. A multi-scale hybrid model will be developed to investigate the early plasma formation, its interaction with the laser beam and the target surface. For the formation of early plasma, a combined molecular dynamics and Monte Carlo model (MD/MC) will be developed to calculate the dynamics of neutrals, electrons, ions, photons and phonons, while considering the interactions among these particles. Since the temporal and spatial computation domain sizes of the combined MD/MC are limited because of computational complexity, the MD/MC will be interfaced with a finite difference model for the domain deep inside the target material, and also interfaced with the hydrodynamic equations for the domain above the target surface to model the plasma/ambient air region. This combined model will reveal detailed information about early plasma formation, and its interaction with the laser beam and the target surface. In the companion experimental study, the interferogram and shadowgraph techniques will be used to realize a more comprehensive measurement and observation of laser-generated plasma and shock waves at different delay times. The experimental results will be used for the validation of the model.Broader Impacts. High energy, ultrashort lasers have applications ranging from pulsed laser fabrication of thin films to laser micro/nano fabrication. Improving the understanding of high energy ultrashort, laser-material interaction can significantly expand the potential applications of these devices. The research will yield information relevant to the future development of suitable lasers for specific applications. The research results will be broadly disseminated at conferences targeted to both industrial and academic audiences, as well as at a dedicated web site. Several undergraduate students will be involved through the summer undergraduate research fellowship (SURF) program administered by the College of Engineering at Purdue, as well as through undergraduate independent projects. Involvement of underrepresented students will be pursued through existing programs such as Women in Engineering Program (WIEP) and the Minority Engineering Program (MEP). The research will be incorporated into an undergraduate manufacturing class, Principles and Practice of Manufacturing Processes. At the Illinois Institute of Technology (IIT), the new findings will be incorporated into a class entitled Advanced Manufacturing Engineering. Undergraduates and minority graduate students will be involved through the Undergraduate Research Fellowships program and a Special Topics class at IIT. Animation demonstration kits based on the project will be shared with the Chicago Public School Students Science Fair, to attract more students (particularly minority students) to become engaged in science and engineering.