Particle acceleration in magnetised shocks produced by laser and pulsed power facilities

激光和脉冲电源设施产生的磁化冲击中的粒子加速

• 批准号: EP/N013379/1
• 负责人: Sergey Lebedev
• 金额: $ 74.64万
• 依托单位: Imperial College London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2016
• 资助国家: 英国
• 起止时间: 2016 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FN013379%2F1
• 关键词: Particle; acceleration; magnetised; shocks; produced

We propose an ambitious multi-institution experimental programme to investigate one of the greatest mysteries in astrophysics: the acceleration mechanism that leads to generation of high energy cosmic rays. The presence of energetic particles in the Universe is a well established fact, with measurements of the cosmic ray (CR) spectrum extending up to astonishing 1e20 eV. In spite of this, the exact mechanism that leads to such high energy particles still remains controversial. The central theme of this proposal is to conduct a programme of linked earth-based experimental and theoretical investigations into CR acceleration mechanisms to address this long running problem. Although many different processes may result in CR acceleration, the present day understanding is that shock waves and turbulence play an essential role in energizing both the electrons and ions present in the interstellar medium. We will perform linked experimental and numerical studies of the acceleration of electrons in strong shocks formed in magnetised plasmas. The shocks will be formed by supersonic plasma flows created by high intensity lasers and Mega-Ampere-level pulsed currents. The first set of experiments will investigate the initial acceleration of electrons, which should allow the formation of electron population with energies significantly exceeding their initial thermal energy. This is expected to occur due to plasma wave turbulence which is excited in the pre-shock plasma by the ions reflected from the shock front, but this mechanism has never been tested by experiment. We will characterise the development of the turbulence and measure the parameters of the accelerated electrons using state-of-the-art diagnostic techniques previously developed by us. In the second set of experiments, we will investigate the so-called diffusive shock acceleration mechanism, which is considered as the most plausible mechanism of cosmic ray acceleration. This will be achieved by injecting sufficiently energetic electrons into the shock, in such a way that these electrons will then sample both the pre- and post-shock regions, performing multiple passages through the shock front as required for this mechanism to operate efficiently. Use of a magnetic spectrometer will allow direct measurements of the energy of the accelerated electrons which will be compared with theoretical predictions. As part of this project we will also perform numerical simulations using state of the art hybrid-MHD and PIC codes and cross-compare the results with our experimental data. The computational and theoretical components of the project will allow us to forge a strong connection between experiment, astrophysical models and observations.The proposed research lies at the border between Plasma Physics and Astrophysics, and will advance the development of the novel research area of Laboratory Astrophysics, which seeks to enhance the understanding of the physics governing the behaviour of astrophysical objects directly via scaled laboratory experiments, combined with computer modelling. Creating the extreme plasma conditions required for scaled reconstruction of astrophysical environments in the laboratory, became possible only recently thanks to the advent of high energy lasers and fast rise-time high-current pulsed power facilities. The similarity between the lab and nature in terms of key dimensionless parameters (e.g. Mach number) is sufficiently close to make such experiments highly relevant. The timeliness of this proposal is also underlined by the growing interest in this field internationally with major efforts in USA (Rochester, Livermore - NIF) and Europe (Bordeaux - LaserMegajoule). The combined expertise of the authors of this proposal and the involvement of international collaborators from Astrophysics community will allow us to create and exploit an unprecedented capability for the Laboratory Astrophysics research and provide both breadth and depth to the programme.

我们提出了一项雄心勃勃的多机构实验计划，以研究天体物理学中最大的谜团之一：导致高能宇宙射线产生的加速机制。宇宙中存在高能粒子是一个公认的事实，宇宙射线 (CR) 光谱的测量值高达惊人的 1e20 eV。尽管如此，产生如此高能粒子的确切机制仍然存在争议。该提案的中心主题是对 CR 加速机制进行一项基于地球的实验和理论研究相结合的计划，以解决这个长期存在的问题。尽管许多不同的过程都可能导致 CR 加速，但目前的理解是，冲击波和湍流在激发星际介质中的电子和离子方面发挥着重要作用。我们将对磁化等离子体中形成的强冲击中电子的加速进行相关的实验和数值研究。冲击将由高强度激光和兆安级脉冲电流产生的超音速等离子体流形成。第一组实验将研究电子的初始加速，这应该允许形成能量显着超过其初始热能的电子群。预计这是由于等离子体波湍流而发生的，等离子体波湍流是由从激波前沿反射的离子在预激波等离子体中激发的，但这种机制从未经过实验测试。我们将使用我们之前开发的最先进的诊断技术来表征湍流的发展并测量加速电子的参数。在第二组实验中，我们将研究所谓的扩散激波加速机制，它被认为是最合理的宇宙射线加速机制。这将通过向激波中注入足够高能的电子来实现，这些电子随后将对激波前和激波后区域进行采样，根据该机制有效运行的需要，多次穿过激波前沿。使用磁谱仪将可以直接测量加速电子的能量，并将其与理论预测进行比较。作为该项目的一部分，我们还将使用最先进的混合 MHD 和 PIC 代码进行数值模拟，并将结果与​​我们的实验数据进行交叉比较。该项目的计算和理论部分将使我们能够在实验、天体物理模型和观测之间建立牢固的联系。拟议的研究位于等离子体物理学和天体物理学之间的边界，并将推动实验室天体物理学这一新研究领域的发展，该领域旨在通过规模化的实验室实验与计算机建模相结合，增强对直接控制天体物理物体行为的物理学的理解。由于高能激光器和快速上升时间高电流脉冲电源设施的出现，在实验室中创造大规模重建天体物理环境所需的极端等离子体条件直到最近才成为可能。实验室与自然在关键无量纲参数（例如马赫数）方面的相似性非常接近，使得此类实验具有高度相关性。国际上对该领域日益增长的兴趣也强调了该提案的及时性，美国（罗彻斯特、利弗莫尔 - NIF）和欧洲（波尔多 - LaserMegajoule）做出了重大努力。该提案作者的综合专业知识以及天体物理学界国际合作者的参与将使我们能够为实验室天体物理学研究创造和利用前所未有的能力，并为该计划提供广度和深度。

项目成果

Stop layer: a flow braking mechanism in space and support from a lab experiment

停止层：空间中的流动制动机制和实验室实验的支持

• DOI: 10.1088/0741-3335/58/6/064001
• 发表时间: 2016
• 期刊: Plasma Physics and Controlled Fusion
• 影响因子: 2.2
• 作者: Haerendel G

Inverse Liner Z-Pinch: An Experimental Pulsed Power Platform for Studying Radiative Shocks

• DOI: 10.1109/tps.2018.2868757
• 发表时间: 2018-10
• 期刊: IEEE Transactions on Plasma Science
• 影响因子: 1.5
• 作者: T. Clayson;Sergey Lebedev;F. Suzuki-Vidal;G. Burdiak;J. Halliday;J. Hare;J. Ma;L. Suttle;E. Tubman

Hydrodynamic and magnetohydrodynamic simulations of wire turbulence

金属丝湍流的流体动力学和磁流体动力学模拟

• DOI: 10.1016/j.hedp.2019.100699
• 发表时间: 2019
• 期刊: High Energy Density Physics
• 影响因子: 1.6
• 作者: Fogerty E

The structure of 3D collisional magnetized bow shocks in pulsed-power-driven plasma flow

脉冲功率驱动等离子体流中 3D 碰撞磁化弓激波的结构

• DOI: 10.48550/arxiv.2208.04535
• 发表时间: 2022
• 作者: Datta R

The structure of bow shocks formed by the interaction of pulsed-power driven magnetised plasma flows with conducting obstacles

• DOI: 10.1063/1.4993187
• 发表时间: 2017-07
• 期刊: Physics of Plasmas
• 影响因子: 2.2
• 作者: G. Burdiak;S. Lebedev;S. Bland;T. Clayson;J. Hare;L. Suttle;F. Suzuki-Vidal;D. C. Garcia