RUI: Studies of Particle Transport in a Non-Neutral Plasma Trap

该奖项是对提交给NSF/美国能源部基础等离子体科学与工程伙伴关系联合征集NSF 09-596的提案的回应。该奖项提供资金支持本科生参与整个研究工作，该工作由美国能源部根据与西方学院的合同单独提供资金(Grant DE-FG02-06ER54882)。本项目研究了由于外加非对称电场而引起的圆柱形非中性等离子体陷阱中的电子输运。之前关于这个项目的工作发现与理论有一些表面上的一致，但也发现了一些重要的不同之处。这笔赠款的工作将集中在根据先前的实验和模拟结果测试一种新的运输模型。在这个模型中，传输是由低速、轴向捕获的粒子主导的，这些粒子通过一个混乱的、无碰撞的过程散射。为了验证这一模型，将进行实验来测量和操纵被捕获的粒子。为了进一步完善模型，将研究低不对称频率下的输运，其中实验与共振粒子理论的分歧最大。最后，这项工作将得到一个简单的粒子模拟的支持，该模拟将扩展到关注以前观察到的混沌动力学。为了避免以前遇到的复杂情况，并在简单条件下验证输运理论，实验工作在专门设计的捕集器中进行。通过使用多达40个墙扇区来创建场不对称性的频谱被简化。电子密度降低了100倍，以减少由于集体效应而引起的非必要的并发症，而沿陷阱轴线运行的偏置导线产生的径向电场保持了通常在高密度等离子体中存在的方位漂移。电子的位置和密度是通过将陷阱中的电子倾倒到涂有荧光粉的屏幕上并分析生成的图像来确定的。然后根据这些图像的时间演化计算了实验传输通量，并与理论模型进行了比较。这些活动有几个更广泛的影响。西方学院在本科生研究参与领域处于全国领先地位，并因其研究和教育的一体化而得到认可。与往年一样，本科生将作为参与者和同事参与这项研究，这些学生将在当地和地区会议上展示他们的研究结果。由于西方大学是全国最多元化的文理学院之一，来自代表性不足群体的学生很可能是研究小组的成员。将通过参加关于非中性等离子体的多学科讲习班(每两至三年举行一次)和建立一个网站，扩大成果的传播，使之超越通常的出版场所和在APS/DPP年度会议上发表的论文。最后，这项研究还有更广泛的科学影响。该项目通过测试等离子体传输的基本理论来促进对等离子体的理解，并将有利于任何需要遏制和操纵非中性等离子体的应用。对新经典传输中涉及的复杂问题的理解在传统(中性)限制装置中也是有价值的。NSF对本科生参与的支持，通过向学生介绍科学研究作为一条可能的职业道路，通过对学生的早期培训，增加了更广泛的教育影响。

This award is made in response to a proposal submitted to and reviewed under the NSF/DOE Partnership in Basic Plasma Science and Engineering joint solicitation NSF 09-596. The award provides funds to support undergraduate participation in the overall research effort, which is being funded separately by the DOE under contract to Occidental College (Grant DE-FG02-06ER54882). This project studies electron transport in a cylindrical non-neutral plasma trap due to the presence of applied asymmetric electric fields. Previous work on this project found some superficial agreement with theory, but also identified significant areas of disagreement. The work of this grant will focus on testing a new model for the transport based on previous experimental and simulation results. In this model, the transport is dominated by low velocity, axially trapped particles that are scattered through a chaotic, collisionless process. To test this model, experiments will be performed to measure and manipulate the trapped particles. To further refine the model, transport at the low asymmetry frequencies will be studied where the experiments diverge most dramatically from resonant particle theory. Finally, this work will be supported with a simple particle simulation which will be extended to focus on previously observed chaotic dynamics. The experimental work is performed in a specially designed trap in order to avoid previously encountered complications and to test transport theory under simple conditions. The spectrum of the field asymmetry is simplified by using up to forty wall sectors to create it. The electron density is reduced by a factor of 100 to reduce non-essential complications due to collective effects, while a biased wire running along the axis of the trap produces a radial electric field which maintains the azimuthal drift normally present in higher density plasmas. Electron position and density are determined by dumping the electrons from the trap onto a phosphor-coated screen and analyzing the resultant image. Experimental transport fluxes are then calculated from the time evolution of these images and compared to theoretical models. There are several broader impacts of the activities. Occidental College is a national leader in the area of undergraduate research participation and has been recognized for its integration of research and education. As in previous years, undergraduate students will be involved as participants and co-workers in this research, and these students will present the results of their research at local and regional meetings. Because Occidental is one of the most diverse of national liberal arts colleges, students from underrepresented groups are likely to be members of the research groups. Dissemination of results will be broadened beyond the usual publication venues and papers given at the annual APS/DPP meeting by participation in the multidisciplinary Workshop on Non-Neutral Plasmas (held every two to three years) and by developing a web site. Finally, there are also scientific broader impacts to this research. This project advances understanding of plasmas by testing a fundamental theory of plasma transport and will benefit any application that requires the containment and manipulation of non-neutral plasmas. An understanding of the complex issues involved in neo-classical transport is also of value in conventional (neutral) confinement devices. The NSF support of undergraduate participation adds a broader educational impact through the early-year training of students by introducing them to scientific research as a possible career path.