ION AND NEUTRAL VELOCITY DISTRIBUTIONS IN MULTI-ION PLASMA SHEATHS

该建议是针对调查的物理多离子鞘，产生的高能离子自发形成双层（鞘）的超音速通量，并创建可用于等离子体辅助蚀刻的高能中性通量。中性蚀刻避免了在微电子工业中使用高能离子蚀刻晶片时发生的衬底充电问题。多离子等离子体鞘层中离子的加速是一个基本的等离子体物理问题，对从空间等离子体到聚变等离子体等系统都有重要的影响。这项建议有两个主要目标。首先是确定额外的离子种类对双层形成在扩大螺旋等离子体的影响，第二，由于电荷交换过程的层中的离子和中性原子之间的动量耦合的测量。拟议活动的基本知识价值将是第一次详细测量等离子体鞘中两种不同离子物种和一种中性物种的流速。离子加速通过前鞘层和鞘层在多离子等离子体还没有完全理解，这个项目将作出重大贡献，这一活跃领域的基础等离子体科学研究。这项工作的更广泛影响涉及在强调基础和应用等离子体物理学之间协同作用的研究环境中培训研究生;提高获得物理学高级学位的妇女的百分比;通过参与尖端研究活动吸引高素质的本科生进入物理学。对半导体的等离子体蚀刻领域的影响也是可能的，因为通过双层加速离子的电荷交换中和产生高能中性原子的显著通量将提供在小于10纳米的尺度下蚀刻硅中的特征的新手段。对等离子体推进领域的影响也很可能是因为等离子体从等离子体推进器中分离是一个重要而尚未解决的问题。

The proposal is directed at investigating the physics of multi-ion sheaths, the generation of supersonic fluxes of energetic ions in spontaneously forming double layers (sheaths), and the creation of fluxes of energetic neutrals that could be used for plasma-aided etching. Neutral etching avoids the problem of substrate charging that occurs when energetic ions are used to etch wafers in the microelectronics industry. The acceleration of ions through sheaths in multi-ion plasmas is a fundamental plasma physics question with important ramifications for systems ranging from space plasmas to fusion plasmas. There are two primary objectives of this proposal. First is the determination of the effect of additional ion species on double layer formation in expanding helicon plasmas, and second, the measurement of the momentum coupling between ions and neutral atoms in the layer due to charge exchange processes. The essential intellectual merit of the proposed activity will be the first detailed measurement of the flow velocities of two different ion species and a single neutral species in a plasma sheath. Ion acceleration through pre-sheaths and sheaths in multi-ion plasmas is not fully understood and this project will make a significant contribution to this active area of fundamental plasma science research. The broader impact of the work involves the training of graduate students in a research environment that emphasizes the synergy between basic and applied plasma physics; improvement of the percentage of women obtaining advanced degrees in physics; and attracting high quality undergraduates into physics through involvement in cutting-edge research activities. Impact on the field of plasma etching of semiconductors is also likely since production of significant fluxes of energetic neutral atoms through charge exchange neutralization of the double layer accelerated ions would provide a new means of etching features in silicon at scales of less than ten nanometers. Impact on the field of plasma propulsion is also likely given that plasma detachment from plasma-based thrusters is an important and unresolved question.