Collaborative Research: Understanding Sheaths and Pre-Sheaths in Plasmas

提案题目：合作研究：了解等离子体中的鞘层和预鞘层主要研究者：Hershkowitz， Noah / Severn， Greg机构：威斯康星大学麦迪逊分校/圣地亚哥大学提案号：本研究解决了关于多物种等离子体鞘鞘-鞘鞘前物理的基础科学问题，这些问题对等离子体科学和技术的许多领域至关重要，包括等离子体推进器、等离子体处理、聚变装置的转移器、Langmuir探针和射频等离子体。80多年后，许多与鞘有关的重要问题将首次得到解决。拟议的实验旨在为理论预测和假设尚未得到验证的各种情况建立鞘和相关预鞘的基本特性。协同研究将在威斯康星大学和圣地亚哥大学进行，以确定鞘前和鞘内等离子体电位分布以及由此产生的与离子加速相关的离子速度分布函数。大部分实验将在赫什科维茨教授的实验室进行。然而，两个校区都在进行LIF诊断开发，并由Severn教授领导。等离子体参数将用两种或两种以上的技术来确定；例如，发射探针的组合，Ar和Xe亚稳离子LIF， Langmuir探针，离子声波的相速度，伪波速度和光学发射光谱。由于（例如）探针的粒子损耗和亚稳态而不是基态离子的LIF测量，诊断具有侵入性或不完全性，因此需要几种诊断的一致性。实验将使用热丝多偶极子，电容，电感和螺旋源，目前在我们的实验室操作。在Ar和Xe等离子体中加入O2、SF6或Cl2将产生负离子。如上所述，许多基于等离子体的技术将从中受益。拟议的研究结果将通过出版物和会议报告在科学界和工业界广泛传播。该小组认为，这些结果很可能会被用在等离子体物理教科书中，并在未来几年被广泛引用。研究生和本科生将参与研究，这些调查中使用的实验将在学生实验课程中使用。在这些调查中使用的相对便宜的桌面实验适合学生的实验课程，允许学生进行最先进的实验。

AWARD Public Abstract Proposal Title: Collaborative Research: Understanding Sheaths and Pre-Sheaths in PlasmasPrincipal Investigator: Hershkowitz, Noah / Severn, Greg Institution: University of Wisconsin-Madison / University of San DiegoProposal No: CBET- 0903783 / CBET- 0903832 This research addresses basic science questions concerning the sheath-presheath physics in multispecies plasmas that are central to many fields of plasma science and technology, including plasma thrusters, plasma processing, divertors of fusion devices, Langmuir probes, and RF plasmas. After more than 80 years, many important questions associated with sheaths will be addressed for the first time.Proposed experiments are aimed at establishing the basic properties of sheaths and associated presheaths for a variety of situations for which theoretical predictions and assumptions have not yet been verified. Coordinated studies will be carried out at the University of Wisconsin and San Diego University to determine the presheath and sheath plasma potential profiles and the resulting ion velocity distribution functions associated with ion acceleration. Most of the experiments are to be carried out in the laboratory of Prof. Hershkowitz. However, LIF diagnostic development is being carried out on both campuses and is led by Prof. Severn. Plasma parameters will be determined with two or more techniques; e.g., combinations of emissive probes, Ar and Xe metastable ion LIF, Langmuir probes, the phase velocities of ion acoustic waves, pseudo-wave velocities and optical emission spectroscopy. Agreement of several diagnostics is needed because of the invasive or incomplete nature of the diagnostics due to (e.g.) particle depletion by probes and LIF measurements of metastable rather than ground state ions. Experiments will employ hot-filament multi-dipole, capacitive, inductive, and helicon sources currently in operation in our laboratory. Negative ions will be produced by adding O2, SF6, or Cl2 into Ar and Xe plasmas. As noted above, many plasma-based technologies would benefit. The results of the proposed research will be disseminated broadly in the scientific community and industry through publications and conference presentations. The panel considered it likely that the results will be used in plasma physics textbooks and will be widely referenced for years to come. Graduate and undergraduate students will participate in the research, and the experiments used in these investigations will be used in student laboratory courses. The relatively inexpensive tabletop experiments used in these investigations are suited to student laboratory courses, permitting students to perform state-of-the-art experiments.