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: 2010450
• 负责人: Nikolai Pogorelov
• 金额: $ 19.72万
• 依托单位: University of Alabama in Huntsville
• 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: 2020-07-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2010450&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.

该项目将在太空和实验室环境中开发一种新的、更准确的稀薄等离子体中的冲击波模型。所谓无碰撞冲击波是发生在高温稀有等离子体中的最基本的现象。天体物理波通过将等离子体流动的动态压力转化为热能来加速粒子、耗散能量，并强烈扰乱它们传播的环境。现代等离子体物理的核心理论问题之一是定量预测冲击波(下游)后面的等离子体状态，给出它前面(上游)的给定参数。大多数直接观测到的无碰撞激波都在日光层中；然而，它们也可以在实验室中产生。该项目的重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，另一方面确定上下游条件之间易于使用的关系，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，并通过与美国-以色列双国科学基金会支持的本古里安大学的合作，让他们参与国际科学合作。无碰撞冲击(CSS)在许多空间物理、天体物理和实验室环境中普遍存在。尽管有60多年的CS研究，但与早期的进展相比，该问题的现状基本上没有变化。将标准的Rankine-Hugoniot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激波前沿的基本离子动力学纳入统计描述，以便一方面避免深入研究离子运动的细节，另一方面放弃与状态方程有关的特殊假设。将使用局部混合和全动力学PIC模拟来验证和改进概率测试粒子方法。这项研究将确保CS物理学向前迈出实质性的一步，因为它提供了一种可以与实际观测进行定量比较的理论。概率方法有望对等离子体物理的其他问题有效，在这些问题中，完全动力学方法目前是不可能的，而基于流体近似的假设是无效的。它相对简单，能够涵盖广泛的冲击参数，使得创建方便的解析公式和/或查找表成为可能，供广泛的等离子体物理学家使用。这也将有助于开发涉及无碰撞冲击的全球磁流体力学模型，特别是能够更准确地预测空间天气。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

The role of pickup ions in the solar wind and its interaction with the local interstellar medium

太阳风中拾取离子的作用及其与当地星际介质的相互作用

• 发表时间: 2021
• 期刊: 43rd COSPAR Scientific Assembly. Held 28 January - 4 February
• 作者: Pogorelov, N.;Zhang, M.;Gedalin, M.;Kim, T.;Roytershteyn, V.;Renfroe, K.
• 通讯作者: Renfroe, K.

Magnetic turbulence in the Very Local Interstellar Medium from macroscales to microscales

从宏观尺度到微观尺度的非常局域星际介质中的磁湍流

• 发表时间: 2021
• 作者: Fraternale, F.;Pogorelov, N.;Burlaga, L.
• 通讯作者: Burlaga, L.

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

Magnetic Field Draping of the Heliopause and Its Consequences for Radio Emission in the Very Local Interstellar Medium

日球层顶的磁场覆盖及其对非常局域星际介质中无线电发射的影响

• DOI: 10.3847/2041-8213/ac14bd
• 发表时间: 2021
• 期刊: The Astrophysical Journal Letters
• 作者: Pogorelov, N. V.;Fraternale, F.;Kim, T. K.;Burlaga, L. F.;Gurnett, D. A.
• 通讯作者: Gurnett, D. A.