Magnetically-Assisted Laser-Induced Plasma Micro-Machining for Flexible and Fast Texturing of Functional Surfaces

能源、环境和健康领域的挑战提出了对灵活和可扩展的微加工工艺的日益增长的需求，这些工艺用于诸如用于组织粘附和防生物污染的纹理化表面、减少工具和发动机系统中的磨损以及用于生物医学设备（诸如针和植入物）的功能表面等应用。该奖项资助了一种新型微加工工艺的研究，该工艺解决了现有的几个挑战，即材料可加工性的限制，以经济可行的材料去除率对大面积进行图案化，以及生成不同尺寸和形状的微特征。 磁辅助激光诱导等离子体微加工技术是利用皮秒激光脉冲在液体介质中诱导等离子体羽流，实现微加工过程中的快速、直接加工。等离子体羽流通过热蒸发和机械侵蚀的组合从工件表面去除材料，以产生具有所需几何形状的机加工特征。该项目旨在通过两种机制利用外部磁场对等离子体羽流的影响来提高加工速度和精度方面的加工能力：（1）通过增加其能量密度，从而提高材料去除率;（2）通过修改其形状，从而几乎直接创建所需的微特征几何形状。研究目的是了解过程的电磁和热机械机制之间的相互作用，即，激光、电介质、等离子体、磁场和工件材料之间的相互作用。实现这一目标的方法包括使用磁流体动力学，粒子在细胞和有限元分析方法，以确定每个相互作用的结果模拟。各种材料的实验，包括钛合金，硅，聚合物，透明，脆性和反射材料，如玻璃，将使用皮秒激光系统与532纳米波长，计算机控制的电磁铁阵列，和焦点变化为基础的计量进行。实验结果将与模拟结果的深度和形状的生成功能和材料去除率进行比较。

Challenges in the energy, environmental, and health sectors present a growing need for flexible and scalable micro-machining processes for applications such as textured surfaces for tissue adhesion and anti-bio-fouling, reduced wear in tooling and engine systems, and functional surfaces for biomedical devices such as needles and implants. This award funds research on a novel micro-machining process that addresses several existing challenges, namely limitations in the machinability of materials, patterning large areas at economically feasible material removal rates, and generating micro-features of different sizes and shapes. A fully realized magnetically-assisted laser induced plasma micro-machining process will be capable of fast and direct generation of micro-features with controlled geometrical characteristics.In magnetically-assisted laser-induced plasma micro-machining, picosecond laser pulses induce a plasma plume within a liquid dielectric. The plasma plume removes material from the workpiece surface by a combination of thermal vaporization and mechanical erosion to create machined features with desired geometry. This project aims to advance processing capabilities in terms of machining rate and precision by utilizing the external magnetic field's influence on the plasma plume through two mechanisms: (1) by increasing its energy density, leading to increased material removal rates; and (2) by modifying its shape, leading to the nearly direct creation of desired micro-feature geometries. The research objective is to understand the interaction between the electromagnetic and thermo-mechanical mechanisms of the process, i.e., interactions between the laser, dielectric, plasma, magnetic field and workpiece material. Methods to achieve this objective include simulations using magneto-hydrodynamic, particle-in-cell and finite element analysis methods to determine the outcomes of each interaction. Experiments with a wide variety of materials, including titanium alloys, silicon, polymers, and transparent, brittle and reflective materials such as glass, will be conducted using a picosecond laser system with a 532 nm wavelength, a computer-controlled array of electromagnets, and focus variation-based metrology. Experimental results will be compared with simulation results in terms of the depth and shape of the generated features and material removal rate.