Measurements of Electron Weibel Instability in a Laboratory Plasma Using Relativistic Electron Beams

使用相对论电子束测量实验室等离子体中的电子韦贝尔不稳定性

• 批准号: 2003354
• 负责人: Chan Joshi
• 金额: $ 60万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-08-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2003354&HistoricalAwards=false
• 关键词: Measurements; Electron; Weibel; Instability; Laboratory

Most of the matter that one can observe in the universe is in a plasma state comprised of electrically charged particles, electrons and ions. It is therefore imperative to understand the behavior of plasmas in order to explain galactic formation, gamma-ray bursts, and our own Sun. Often, the temperature of electrons in a plasma is hotter in one direction than in the other. Such plasmas are said to be anisotropic. An anisotropic plasma eventually becomes isotropic -- reaching the same temperature in all three dimensions of space -- by a process known as the Weibel instability. The Weibel instability was predicted by Weibel almost 50 years ago, but it has been impossible to check the theory of how rapidly this instability grows and why it eventually stops growing (saturates) because it has not been possible to generate a plasma with known temperature anisotropy in the laboratory. This project aims to measure the generation and saturation of the Weibel instability for the first time. This experimental work will be performed by the University of California - Los Angeles team at the Accelerator Test Facility at Brookhaven National Laboratory, and will involve training of a graduate student and a postdoctoral associate in plasma and accelerator science.Highly anisotropic plasmas can be produced by optical field ionization of He gas using a circularly polarized laser pulse, resulting in a plasma that is very hot in the transverse direction but rather cold in the direction of propagation of the laser. Such a plasma undergoes a hierarchy of plasma kinetic instabilities, starting with the two stream instability and current filamentation instability that reduce the plasma anisotropy from ~100 to less than 10 in a pico-second. Thereafter, the electron Weibel instability begins to grow, seeded by coalescence of currents associated with the filamentation instability. The pure Weibel instability is characterized by rapid growth of a static magnetic field with a broad wavenumber spectrum. This wavenumber spectrum quickly narrows to a fairly well defined, most unstable mode that has helicoid topology. This work will measure the exponential growth and saturation of this magnetic field and its topology for the first time. To measure the dynamics of the Weibel B-field, a relativistic electron beam will be used as a probe. During its passage through the plasma, the probe electrons will be deflected by the transverse component of the helicoid magnetic field. These deflections can be visualized as probe electron density structures on a screen placed some distance away from the plasma. From images taken at different times, the evolution of the k spectrum, its spectral amplitude and 2D spatial profile of the B-field can be obtained, thereby allowing a quantitative comparison of experiment with kinetic theory of the Weibel instability.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

人们在宇宙中观察到的大多数物质都处于等离子体状态，由带电的粒子、电子和离子组成。因此，为了解释星系的形成、伽马射线爆发和我们自己的太阳，了解等离子体的行为是非常必要的。通常，等离子体中电子的温度在一个方向上比在另一个方向上更热。这种等离子体被认为是各向异性的。各向异性等离子体最终变得各向同性--在空间的所有三个维度达到相同的温度--通过一种被称为韦伯不稳定性的过程。韦伯不稳定性是由韦伯在近50年前预测的，但一直无法检验这种不稳定性增长有多快以及为什么它最终停止增长(饱和)的理论，因为它不可能在实验室中产生具有已知温度各向异性的等离子体。该项目旨在首次测量韦伯不稳定性的产生和饱和程度。这项实验工作将由加州大学洛杉矶分校在布鲁克海文国家实验室的加速器测试设施进行，将涉及等离子体和加速器科学方面的一名研究生和一名博士后助理的培训。通过使用圆偏振激光脉冲对He气体进行光场电离，可以产生高度各向异性的等离子体，导致等离子体在横向非常热，但在激光传播方向非常冷。这样的等离子体经历了等离子体运动不稳定性的分级，从双流不稳定性和电流丝状不稳定性开始，它们在皮秒内将等离子体的各向异性从~100降低到小于10。此后，电子韦伯不稳定性开始增长，这是由与成丝不稳定性相关的电流的聚合所孕育的。纯魏贝尔不稳定性的特征是具有宽波数谱的静磁场的快速增长。这个波数谱很快缩小到一个定义相当好的、最不稳定的模式，它具有螺旋面的拓扑结构。这项工作将首次测量该磁场的指数增长和饱和及其拓扑结构。为了测量韦贝尔B场的动力学，将使用相对论电子束作为探针。在穿过等离子体的过程中，探测电子将被螺旋面磁场的横向分量偏转。这些偏转可以可视化为屏幕上的探测器电子密度结构，放置在离等离子体一段距离的地方。从不同时间拍摄的图像中，可以获得B场的k谱、其谱幅度和2D空间轮廓的演变，从而可以将实验与威布尔不稳定性的动量理论进行定量比较。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Ionization induced plasma grating and its applications in strong-field ionization measurements

• DOI: 10.1088/1361-6587/ac1751
• 发表时间: 2021-06
• 期刊: Plasma Physics and Controlled Fusion
• 影响因子: 2.2
• 作者: Chaojie Zhang;Z. Nie;Yipeng Wu;M. Sinclair;Chengkun Huang;K. Marsh;C. Joshi

Thomson scattering diagnostics of nonthermal plasma from particle-in-cell simulations

通过细胞内粒子模拟对非热等离子体进行汤姆逊散射诊断

• 发表时间: 2023
• 期刊: Advanced Accelerator Concepts Workshop 2022
• 作者: Farrell, Audrey;Zhang, Chaojie;Wu, Yipeng;Nie, Zan;Nambu, Noa;Sinclair, Mitchell;Marsh, Kenneth;Joshi, Chandrasekhar
• 通讯作者: Joshi, Chandrasekhar

Predominant contribution of direct laser acceleration to high-energy electron spectra in a low-density self-modulated laser wakefield accelerator

低密度自调制激光尾场加速器中直接激光加速对高能电子谱的主要贡献

• DOI: 10.1103/physrevaccelbeams.24.011302
• 发表时间: 2021
• 期刊: Physical Review Accelerators and Beams
• 影响因子: 1.7
• 作者: King, P. M.;Miller, K.;Lemos, N.;Shaw, J. L.;Kraus, B. F.;Thibodeau, M.;Hegelich, B. M.;Hinojosa, J.;Michel, P.;Joshi, C.
• 通讯作者: Joshi, C.

Quantum electronics enabled by high-field physics

高场物理实现的量子电子学

• DOI: 10.1364/nlo.2023.w1b.7
• 发表时间: 2023
• 期刊: Optica Nonlinear Optics Topical Meeting 2023
• 作者: Nambu, Noa;Nie, Zan;Marsh, Ken;Matteo, Dan;Tochitsky, Sergei;Morales, Felipe;Ivanov, Misha;Carlstroem, Stefanos;Patchkovskii, Serguei;Smirnova, Olga
• 通讯作者: Smirnova, Olga

X-ray Source Development for High Energy Density Science Using Picosecond Relativistic Laser Interaction with Underdense Plasma

利用皮秒相对论激光与低密度等离子体相互作用开发高能量密度科学 X 射线源

• 发表时间: 2023
• 期刊: Advanced Accelerator Concepts Workshop 2022
• 作者: Sinclair, Mitchell;Pagano, Isabella;Lemos, Nuno;Shaw, Jessica L.;Miller, Kyle G.;Aghedo, Adeola;Arrowsmith, Charles D.;King, Paul M.;Marsh, Kenneth A.;Albert, Felicie
• 通讯作者: Albert, Felicie