NSF-BSF: Collaborative Research: Rankine-Hugoniot Conditions Relating the Gyrotropic Regions of Collisionless Shocks in Non-Thermal Plasma

NSF-BSF：合作研究：与非热等离子体中无碰撞激波的回旋区域相关的兰金-于戈尼奥条件

• 批准号: 2010144
• 负责人: Vadim Roytershteyn
• 金额: $ 24.56万
• 依托单位: SPACE SCIENCE INSTITUTE
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-07-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2010144&HistoricalAwards=false
• 关键词: NSF; BSF; Collaborative; Research; Rankine

This project will develop a new and more accurate model of shock waves in rarefied plasmas in space and laboratory environments. So-called collisionless shock waves belong to the most fundamental phenomena occurring in hot and rarified plasmas. Astrophysical waves accelerate particles, dissipate energy, and strongly perturb the environment they propagate through by converting dynamic pressure of a plasma flow into thermal energy. One of the central theoretical issues in modern plasma physics is a quantitative prediction of the plasma state behind a shock wave (downstream) for given parameters in front of it (upstream). The majority of directly observed collisionless shocks are in the heliosphere; however, they can also be created in a laboratory. The grand challenge of this project is to develop a new theoretical approach that would, on the one hand, account for the details of how individual particles interact with shock waves in collisionless plasma, but on the other hand, identify easy-to-use relationships between upstream and downstream conditions, similar to those widely used for shock waves in aerodynamics. The project will train students and postdocs in computational science and plasma physics, as well as expose them to international science cooperation via collaboration with Ben Gurion University supported by the U.S. - Israel Binational Science Foundation.Collisionless shocks (CSs) are ubiquitous in many space physics, astrophysics, and laboratory settings. Despite more than six decades of CS research, the present status of the problem remains essentially unchanged in comparison to the early advances. Application of standard Rankine–Hugoniot conditions to CSs is either invalid or highly inaccurate. The objective of this research is to incorporate the essential ion dynamics at shock fronts into a statistical description which would make it possible, on the one hand, to avoid going into details of ion motion and, on the other hand, abandon ad hoc assumptions related to the equations of state. Local hybrid and fully-kinetic PIC simulations will be used to validate and improve on the probabilistic, test-particle approach. This research will ensure a substantial step forward in the CS physics by providing a theory which can be compared quantitatively with real observations. The probabilistic approach is expected to be efficient for other problems of plasma physics, where the full kinetic approach is currently impossible, while the assumptions based on the fluid approximation are not valid. Its relative simplicity and ability to cover a wide range of shock parameters makes it possible to create convenient analytic formulae and/or lookup tables to be used by a wide range of plasma physicists. These will also be useful for the development of global magnetohydrodynamic models involving collisionless shocks enabling, in particular, more accurate forecasting of space weather.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.

该项目将开发一种新的、更精确的空间和实验室环境中稀薄等离子体冲击波模型。 所谓的无碰撞冲击波属于发生在高温和稀薄等离子体中的最基本的现象。天体物理波加速粒子，耗散能量，并通过将等离子体流的动态压力转换为热能来强烈扰动它们传播的环境。 现代等离子体物理学的中心理论问题之一是对冲击波（下游）后面的等离子体状态的定量预测，以确定冲击波前面（上游）的参数。大多数直接观测到的非碰撞激波都在日球层中;然而，它们也可以在实验室中产生。 该项目的巨大挑战是开发一种新的理论方法，一方面，解释单个粒子如何与无碰撞等离子体中的冲击波相互作用的细节，但另一方面，确定上游和下游条件之间的易于使用的关系，类似于空气动力学中广泛使用的冲击波。 该项目将对学生和博士后进行计算科学和等离子体物理方面的培训，并通过与本古里安大学的合作，让他们接触到由美国-以色列两国科学基金会支持的国际科学合作。无碰撞冲击（CS）在许多空间物理学，天体物理学和实验室环境中无处不在。 尽管CS研究已经进行了60多年，但与早期进展相比，该问题的现状基本上没有变化。 将标准的朗肯-雨果尼奥条件应用于CS要么是无效的，要么是非常不准确的。 这项研究的目的是将基本的离子动力学在冲击波前的统计描述，这将使它成为可能，一方面，以避免进入离子运动的细节，另一方面，放弃特设的假设有关的状态方程。 本地混合动力和全动力PIC模拟将用于验证和改进概率，测试粒子的方法。这项研究将确保在CS物理学的实质性的一步，提供了一个理论，可以与真实的观测定量比较。概率的方法预计将是有效的等离子体物理学的其他问题，其中全动力学的方法是目前不可能的，而基于流体近似的假设是无效的。它的相对简单性和覆盖范围广泛的冲击参数的能力，使它有可能创建方便的分析公式和/或查找表，用于广泛的等离子体物理学家。这也将有助于开发涉及无碰撞冲击的全球磁流体动力学模型，特别是能够更准确地预报空间天气，这一奖项反映了国家科学基金会的法定使命，并被认为值得通过利用基金会的知识价值和更广泛的影响审查标准进行评价而予以支持。

项目成果

Change of Rankine–Hugoniot Relations during Postshock Relaxation of Anisotropic Distributions

各向异性分布震后弛豫过程中Rankine-Hugoniot关系的变化

• DOI: 10.3847/1538-4357/ac958d
• 发表时间: 2022
• 期刊: The Astrophysical Journal
• 作者: Gedalin, Michael;Golan, Michal;Pogorelov, Nikolai V.;Roytershteyn, Vadim
• 通讯作者: Roytershteyn, Vadim

Probabilities of ion scattering at the shock front

激波前沿离子散射的概率

• DOI: 10.1017/s0022377822000034
• 发表时间: 2022
• 期刊: Journal of Plasma Physics
• 影响因子: 2.5
• 作者: Gedalin, Michael;Pogorelov, Nikolai V.;Roytershteyn, Vadim
• 通讯作者: Roytershteyn, Vadim

Boundary Conditions at the Heliospheric Termination Shock with Pickup Ions

拾取离子日光层终止激波的边界条件

• DOI: 10.3847/1538-4357/ac05b7
• 发表时间: 2021
• 期刊: The Astrophysical Journal
• 作者: Gedalin, Michael;Pogorelov, Nikolai V.;Roytershteyn, Vadim
• 通讯作者: Roytershteyn, Vadim

Role of the overshoot in the shock self-organization

超调在激波自组织中的作用

• DOI: 10.1017/s0022377823000090
• 发表时间: 2023
• 期刊: Journal of Plasma Physics
• 影响因子: 2.5
• 作者: Gedalin, Michael;Dimmock, Andrew P.;Russell, Christopher T.;Pogorelov, Nikolai V.;Roytershteyn, Vadim
• 通讯作者: Roytershteyn, Vadim

Scattering of Ions at a Rippled Shock

波纹冲击下离子的散射

• DOI: 10.3847/1538-4357/acd63c
• 发表时间: 2023
• 期刊: The Astrophysical Journal
• 作者: Gedalin, Michael;Pogorelov, Nikolai V.;Roytershteyn, Vadim
• 通讯作者: Roytershteyn, Vadim