Realistic Treatment of Plasma-Surface Interactions in Simulations of Low Temperature Plasmas: From a New Diagnostic to Optimization of Process Control

该项目将开发一种新的实验诊断和改进的计算模型，以表征材料表面与低温等离子体之间的相互作用，低温等离子体是由电子、离子和中性原子和分子组成的弱电离气体。低温等离子体对现代生活至关重要，因为它们是制造从笔记本电脑和智能手机到显示器和太阳能电池等各种高科技产品的基础。它们也适用于各种医疗应用，如医疗设备的消毒和伤口愈合。所有这些应用都是基于等离子体以可控的方式诱导不同表面反应的能力。为了优化这些应用，等离子体模拟，包括等离子体表面相互作用的现实实现，是至关重要的。在这个项目中，将开发一种新的诊断方法来测量等离子体表面相互作用物理的关键方面，并将结果实施到计算模型中。这项研究的结果也将被纳入低温等离子体科学的研究生课程中。大多数电容式射频等离子体（CCP）的模拟只包括恒定的离子诱导电子发射和猜测概率下的电子反射。任何依赖于入射粒子能量、角度和表面材料以及其他影响都被忽略。这导致了对粒子加热动力学和通量-能量分布函数（FEDF）的不正确描述。对于许多表面材料和气体，在改变表面条件的等离子体存在的情况下，由电子、离子和中性撞击以及粒子反射和溅射率引起的二次电子发射系数是未知的。本课题将开发一种新的基于仿真的诊断方法，利用发射光谱法测量等离子体中的有效伽马系数。不同入射粒子种类的真实能量和表面依赖的电子发射和反射系数将被实现到ccp的PIC模拟中。模拟程序将以实验为基准，并研究实际表面系数对不同粒子种类的电子加热动力学和fedf控制的影响。所有的调查都将结合最先进的模拟和实验。

This project will develop a new experimental diagnostic and an improved computational model to characterize interactions between a material surface and a low temperature plasma, a weakly ionized gas composed of electrons, ions, and neutral atoms and molecules. Low temperature plasmas are essential for modern life as they form the basis for manufacturing a variety of high-technology products ranging from laptops and smartphones to displays and solar cells. They are also relevant for a variety of medical applications such as sterilization of medical equipment and wound healing. All these applications are based on the ability of the plasma to induce distinct surface reactions in a controlled way. In order to optimize these applications, plasma simulations, including a realistic implementation of plasma-surface interactions, are crucial. In this project, a new diagnostic to measure key aspects of the plasma-surface interaction physics will be developed, and results will be implemented into a computational model. Results obtained from this research will also be incorporated into graduate level lectures on low temperature plasma science.Most simulations of capacitive radio frequency plasmas (CCP) only include constant ion induced electron emission and electron reflection at guessed probabilities. Any dependencies on the incident particle energy, angle, and surface material as well as other effects are neglected. This leads to an incorrect description of the particle heating dynamic and flux-energy distribution functions (FEDF). For many surface materials and gases secondary electron emission coefficients induced by electron, ion, and neutral impact as well as particle reflection and sputter rates are unknown in the presence of plasmas that alter the surface conditions. In this project, a novel simulation based diagnostic to measure effective gamma-coefficient by Optical Emission Spectroscopy in the plasma will be developed. Realistic energy and surface dependent electron emission and reflection coefficients for different incident particle species will then be implemented into PIC simulations of CCPs. The simulation code will be benchmarked against experiments and the effects of realistic surface coefficients on the electron heating dynamics and the control of FEDFs of different particle species will be studied. All investigations will combine state-of-the-art simulations with experiments.