激光等离子体去除微纳颗粒的热力学研究  

Thermodynamics of laser plasma removal of micro and nano-particles

作　　者：罗菊 冯国英[1] 韩敬华[1] 沈雄 张丽君 丁坤艳 Luo Ju;Feng Guo-Ying;Han Jing-Hua;Shen Xiong;Zhang Li-Jun;Ding Kun-Yan(College of Electronics and Information Engineering,Sichuan University,Chengdu 610065,China)

机构地区：[1]四川大学电子信息学院,四川610065

出　　处：《物理学报》2020年第8期138-146,共9页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11574221);四川省重点研发计划(批准号:2019YFG0263)资助的课题.

摘　　要：微杂质污染一直是影响精密器件制造质量和使用寿命的关键因素之一.对于微纳米杂质颗粒用传统的清洗方式(超声清洗等)难以去除,而激光等离子体冲击波具有高压特性,可以实现纳米量级杂质颗粒的去除,具有很大的应用潜力.本文主要研究了激光等离子体去除微纳米颗粒过程中的热力学效应:实验研究了激光等离子体在不同脉冲数下对Si基底上Al颗粒去除后的颗粒形貌变化,发现大颗粒会发生破碎而转变成小颗粒,一些颗粒达到熔点后发生相变形成光滑球体,这源于等离子体的热力学效应共同作用的结果.为了研究微粒物态转化过程,基于冲击波传播理论研究,得到冲击波压强与温度特性的演化规律;同时,利用有限元模拟方式研究激光等离子冲击波压强和温度对微粒作用规律,得到了颗粒内随时间变化的应力分布和温度分布,并在此基础上得到等离子体对颗粒的热力学作用机制.Micro-impurity pollution is always one of the key factors affecting the quality and service life of precision devices. Micro-nano impurity particles are difficult to remove by traditional cleaning methods(ultrasonic cleaning, etc.) and low removal efficiency by laser cleaning methods(dry laser cleaning, etc.). The laser plasma shock wave has high pressure and high temperature characteristics, which can remove nano-scaled impurity particles, and has great potential applications. In this work, we mainly study the thermodynamic effect of the laser plasma in the process of removing micro-and nano-particles. In this work, the Al particles on the Si substrate are removed by laser plasma shock wave, and the transformation of the particle state is discussed through the changes of the experimental sample morphology after different pulse effects. The experimental results show as follows With the increase of the pulse number, the micro-and nano-particle residues gradually decrease. At the same time, on the surface of the sample after these particles are removed, it can be found that large particles break up into small particles, and some of the particles will change into smooth spheres when their temperatures reach the melting point. These phenomena are the result of the interaction of the thermodynamic effect of the plasma. In order to study the transformation process of particle state, based on the plasma shock wave propagation theory, the evolution law of pressure characteristic and temperature characteristic of shock wave are obtained. From the evolution law, it can be seen that with the increase of shock wave radius, the pressure and temperature gradually decrease. When the shock wave propagates to the surface of a sample, it can reach the compression threshold and correspondingly the surface temperature arrives at melting temperature of particles, which are consistent with the experimental results. By using the finite element simulation method, the pressure and temperature of laser plasma shock wave acting on particle

关 键 词：等离子体冲击波 颗粒破碎 颗粒相变 热力学分析 

分 类 号：TN249[电子电信—物理电子学] O53[理学—等离子体物理]