Systematically characterising the exotic material properties of weakly collisional plasmas

系统地表征弱碰撞等离子体的奇异材料特性

• 批准号: MR/W006723/1
• 负责人: Archie Bott
• 金额: $ 129.68万
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=MR%2FW006723%2F1
• 关键词: Systematically; characterising; exotic; material; properties

Many of the most challenging conundrums currently being addressed by frontier scientific research in astrophysics involve interactions between exotic objects of colossal sizes and/or energies, typically resulting in instances of extraordinary energy release: - the electromagnetic fireworks accompanying black-hole mergers, which are now observable with the advent of gravitational- wave and multi-messenger astronomy; - galaxy formation in clusters; - accretion discs and jets, which are now serially observable by the Event Horizon radio-telescope network; - gamma-ray and fast radio bursts; ultra-high-energy cosmic rays; and many other occurrences. To model these phenomena, a key challenge is to have a detailed understanding of the dilute hot gas (known as `plasma') making up the astrophysical environments where these events occur. Unsurprisingly, this plasma is believed to behave very differently to the gases we all encounter in everyday life, on account of being millions of degrees hotter, and one sextillionth the density! While this state of matter has been studied by physicists for nearly a century - most famously, in the contexts of stars and nuclear fusion energy research - there remain a number of surprisingly fundamental uncertainties about its properties: for example, how do plasmas conduct heat, and what is their viscosity? However, recent technological advances in both our computing capabilities and high-energy laser facilities mean that we can now investigate the behaviour of plasmas as never before in the laboratory and on supercomputers. In this research project, I will be undertaking a systematic programme that will significantly advance our understanding of the fundamental properties of the type of plasma typically encountered in astrophysical environments (whose thermal energy exceeds their magnetic energy). More specifically, I will run numerical simulations with state-of-the-art codes to investigate several different characteristics: viscosity, thermal and electrical conductivity, and the spontaneous generation of charged particles with anomalously high energies. I am particularly interested in behaviours which depart markedly from conventional gases. I will then test theoretical frameworks developed in "laboratory astrophysics" experiments, which use lasers to realise extreme conditions on Earth with many similarities to relevant astrophysical environments. In addition to the astrophysical observations, I am also interested in leveraging anomalous properties of magnetised plasmas to aid inertial confinement fusion (ICF) efforts. In ICF schemes, a small capsule of deuterium-tritium fuel is ignited using laser beams; if the scheme is successful, the resulting nuclear fusion reactions produce much more energy than initially applied with the lasers. At present, successful ICF schemes have not yet been achieved; however, I believe that significant improvements to current attempts could be attained by considered use of applied magnetic fields.

天体物理学前沿科学研究目前正在解决的许多最具挑战性的难题涉及巨型天体和(或)能量型奇异天体之间的相互作用，通常会导致发生异常能量释放的情况：--伴随着黑洞合并而产生的电磁烟花，现在人们可以在引力波和多信使天文学的作用下观察到这一现象；--星系群的形成；--现在可以通过Event Horizon射电望远镜网络连续观测到的吸积盘和喷流；--伽玛射线和快速射电爆发；--超高能宇宙射线；以及许多其他事件。为了模拟这些现象，一个关键的挑战是详细了解组成这些事件发生的天体物理环境的稀热气体(称为“等离子体”)。毫不奇怪，这种等离子体的行为被认为与我们日常生活中遇到的气体非常不同，因为它的温度高出数百万度，密度高出六分之一！尽管物理学家已经研究这种物质状态近一个世纪了--最著名的是在恒星和核聚变能源研究的背景下--但关于它的性质仍然存在一些令人惊讶的根本不确定性：例如，等离子体是如何传导热量的，它们的粘度是多少？然而，最近在我们的计算能力和高能激光设备方面的技术进步意味着，我们现在可以在实验室和超级计算机上前所未有地研究等离子体的行为。在这个研究项目中，我将进行一项系统的计划，这将大大促进我们对天体物理环境中常见的等离子体类型(其热能超过磁能)的基本性质的理解。更具体地说，我将用最先进的代码进行数值模拟，以研究几个不同的特征：粘度、热导率和电导率，以及具有异常高能量的带电粒子的自发生成。我特别感兴趣的是那些明显不同于传统气体的行为。然后，我将测试在“实验室天体物理”实验中开发的理论框架，这些实验使用激光来实现地球上与相关天体物理环境有许多相似之处的极端条件。除了天体物理观测，我还对利用磁化等离子体的反常性质来帮助惯性约束聚变(ICF)的努力感兴趣。在ICF方案中，用激光点燃一个小的重氚燃料胶囊；如果方案成功，所产生的核聚变反应产生的能量比最初使用激光产生的能量要多得多。目前，成功的ICF方案尚未实现；但我相信，通过考虑使用外加磁场，可以显著改进目前的尝试。

项目成果

Quantitative proton radiography and shadowgraphy for arbitrary intensities

任意强度的定量质子射线照相和阴影照相

• DOI: 10.1016/j.hedp.2023.101067
• 发表时间: 2023
• 期刊: High Energy Density Physics
• 影响因子: 1.6
• 作者: Davies J

Proton imaging of high-energy-density laboratory plasmas

• DOI: 10.1103/revmodphys.95.045007
• 发表时间: 2022-12
• 期刊: Reviews of Modern Physics
• 影响因子: 44.1
• 作者: D. Schaeffer;A. Bott;M. Borghesi;K. Flippo;W. Fox;J. Fuchs;Chikang Li;F. Séguin;Hye-Sook Park;P. Tzeferacos;L. Willingale