Charged Particulates in Low-temperature Plasmas

提出了低温等离子体含粒子的实验和理论研究。等离子体是一种电离气体，在这项工作中，我们将集中研究在工业中广泛用于制造半导体、光学材料和磁性介质的弱电离等离子体。在等离子体中，微粒（即微米大小的尘埃粒子）会带电。它们也可以通过收集等离子体中的溅射原子来增大尺寸。在等离子体处理的工业应用中，微粒是一个代价高昂的问题，因为它们会落到基材上并污染基材。这就是这项工作的动机。实验将观察粉尘颗粒的电荷随时间和密度的变化。这些测量将采用光学检测平行平板射频等离子体中的颗粒，结果将用于测试等离子体中颗粒充电的理论。将进行理论建模来模拟带电颗粒对离子的捕获。带负电荷的颗粒可以在有限的轨道上捕获正离子，这导致带电颗粒所经历的净电力的减少。该模型将采用离子运动的数值模拟，包括与中性原子的碰撞以及带电颗粒产生的电力。

An experimental and theoretical study is proposed for low temperature plasmas that contain particulates. A plasma is an ionized gas, and in this work we will concentrate on weakly- ionized plasmas of the kind that are used widely in industry for manufacturing semiconductors, optical materials, and magnetic media. In a plasma, particulates (i.e. micron-size dust particles) become electrically charged. They also may grow in size by collecting sputtered atoms in the plasma. Particulates are a costly problem industrial uses of plasma processing because they can fall to a substrate and contaminate it. This is the motivation for this work. Experiments will be carried out to observe the time and density dependence of electrical charging of dust grains. These measurements will employ optical detection of grains in parallel-plate radio-frequency plasmas, and the results will be used to test theories of particulate charging in plasmas. Theoretical modeling will be performed to simulate the trapping of ions by charged grains. Negatively charged grains can trap positive ions in confined orbits, and this cause a reduction in the net electric forces that the charged grains experience. This modeling will employ numerical simulations of the motion of ions, including collisions with neutral atoms as well as the electric force created by charged grains.