Determining the Cross-Scale Coupling whereby Magnetohydrodynamics (MHD) Solar Eruptions Produce Energetic Electrons and X-Rays

确定磁流体动力学 (MHD) 太阳喷发产生高能电子和 X 射线的跨尺度耦合

• 批准号: 1914599
• 负责人: Paul Bellan
• 金额: $ 45万
• 依托单位: California Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-07-01 至 2022-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1914599&HistoricalAwards=false
• 关键词: Determining; Cross; Scale; Coupling; whereby

Constantly-evolving, plasma-filled magnetic arches that are thousands of times bigger than the Earth cover much of the surface of the Sun. These arches sometimes suddenly erupt and eject into space a mix of plasma, magnetic field, energetic electrons/ions, X-rays, as well as copious waves. The detritus of this eruption can wreak havoc on Earth's magnetic field creating aurora, damaging spacecraft, disrupting radio communications, and in extreme circumstances, knocking out electric power grids. The large-scale evolution of the pressure, flow, magnetic fields and electric currents in these arches is described quite well by a set of equations called magnetohydrodynamics (MHD). However, MHD cannot explain why these eruptions occur nor why they generate energetic particles and X-rays because MHD does not describe the very fine-scale physics responsible for these critical phenomena. Laboratory plasmas governed by the same MHD physics as solar plasmas will be arranged to similarly evolve and erupt but in a reproducible way. The transition from large-scale MHD behavior to fine-scale non-MHD behavior producing X-rays and waves will be investigated by observing thousands of controlled eruptions using advanced diagnostics. The research project will be done by the PI assisted by a graduate student and undergraduates working as summer interns or part-time academic-year researchers. The knowledge gained from this research will advance the national health, prosperity, and secure the national defense because energetic solar particles and X-rays can damage spacecraft and harm astronauts while the disruption of Earth's magnetic field can damage electric power grids and adversely affect communications systems.This three-year research project will investigate the cross-scale coupling between MHD eruptive phenomena and fine-scale non-MHD phenomena that produce X-rays, energetic particles, and waves. The research will determine the mechanism by which the X-rays and whistler waves are generated. Preliminary evidence suggests this happens when the Rayleigh-Taylor ripples choke the jet cross-section to be of the order of the ion skin depth at which point MHD fails and a kinetic instability ensues. This kinetic instability is presumed to greatly enhance the local resistivity and thus interrupt the electric current. This current interruption is presumed to cause a large inductive voltage spike that accelerates a small fraction of the electrons to extremely high energy. Brehmsstrahlung from the collision of these fast electrons is then presumed to produce the observed X-ray burst. This working hypothesis will be tested by scanning parameters to check the presumption that the inductive voltage spike is associated with choking the current cross-section. The scaling of this mechanism to the solar corona will be investigated. While scaling of the MHD evolution is straightforward, scaling of the fine-scale non-MHD phenomena requires explaining how MHD couples to the ion depth scale in the corona. This is challenging because in the solar corona the MHD and ion skin depth scales differ by at least 100,000. The hypothesis is that coupling results from the MHD structures having a fractal character like the twisted strands of a rope being composed of still smaller twisted strands. Plasma-filled magnetic flux tubes would be like the rope strands and the finest scale strands would be of the order of the ion-skin depth. Bundles of flux ropes (strands) will be produced in the experiment and tested to see if individual strands become Rayleigh-Taylor unstable when the entire bundle is laterally accelerated. Coupling between the MHD scale (jet, kinks, Rayleigh-Taylor) and the non-MHD scale (energetic particles, X-rays, whistler waves) will be determined and used to model how solar eruptions generate energetic particles, X-rays, and waves. The research and EPO agenda of this project supports the Strategic Goals of the AGS Division in discovery, learning, diversity, and interdisciplinary research.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.

不断变化的，填充等离子体的磁拱，比地球大数千倍覆盖太阳的大部分表面。 这些拱门有时突然突然爆发并弹射到空间中，混合了等离子体，磁场，能量电子/离子，X射线以及大量波。 这次喷发的碎屑会对地球磁场造成严重破坏，从而形成极光，破坏航天器，破坏无线电通信，并在极端情况下，敲出电力网格。 这些拱门中压力，流量，磁场和电流的大规模演变很好地描述了一组称为磁性水力动力学（MHD）的方程式。 但是，MHD无法解释为什么这些喷发发生，也不能解释为什么它们会产生能量颗粒和X射线，因为MHD并未描述负责这些关键现象的非常细的物理学。 由与太阳等离子体相同的MHD物理学管理的实验室等离子体将被安排为类似的进化和爆发，但以可重现的方式进行。 从大规模MHD行为到产生X射线和波浪的细尺度非MHD行为的过渡将通过使用高级诊断剂观察数千次受控喷发进行研究。 该研究项目将由PI在研究生和本科生作为暑期实习生或兼职学年研究人员协助的PI完成。 The knowledge gained from this research will advance the national health, prosperity, and secure the national defense because energetic solar particles and X-rays can damage spacecraft and harm astronauts while the disruption of Earth's magnetic field can damage electric power grids and adversely affect communications systems.This three-year research project will investigate the cross-scale coupling between MHD eruptive phenomena and fine-scale non-MHD phenomena that produce X-rays,能量颗粒和波。 该研究将确定产生X射线和惠斯勒波的机制。 初步证据表明，当雷利 - 泰勒（Rayleigh-Taylor）涟漪窒息射流横截面为离子皮肤深度的顺序时，就会发生这种情况。 假定这种动力学不稳定是为了大大提高局部电阻率，从而中断了电流。 假定这种电流中断会导致大型电感电压尖峰，从而将一小部分电子加速到极高的能量。 然后推定这些快速电子的碰撞中的brehmsstrahlung产生观察到的X射线爆发。 该工作假设将通过扫描参数进行测试，以检查电感电压尖峰与窒息当前横截面有关的推测。 将研究这种机制向太阳能电晕的缩放。 虽然MHD演化的缩放是直接的，但细尺度非MHD现象的缩放需要解释MHD夫妇如何在Corona中的离子深度尺度上。 这是具有挑战性的，因为在太阳能电晕中，MHD和离子皮肤深度尺度至少有100,000。假设是，耦合是由具有分形特征的MHD结构所产生的，例如由仍然较小的扭曲链组成的绳索的扭曲链。 充满等离子体的磁通管就像绳索一样，最好的尺度链将是离子剥离深度的顺序。 在实验中将产生一束通量绳（链），并进行了测试，以查看当整个捆绑包的横向加速时，单个链是否变为Rayleigh-Taylor不稳定。 将确定并使用MHD量表（Jet，Kinks，Rayleigh-Taylor）和非MHD量表（能量颗粒，X射线，惠斯勒波）之间的耦合，并用于模拟太阳喷发如何产生能量颗粒，X射线和波。 该项目的研究和EPO议程支持了AGS部门在发现，学习，多样性和跨学科研究方面的战略目标。该奖项反映了NSF的法定任务，并认为值得通过基金会的知识分子优点和更广泛影响的评估标准通过评估来获得支持。

项目成果

Determination of a macro- to micro-scale progression leading to a magnetized plasma disruption

确定导致磁化等离子体破坏的宏观到微观进程

• DOI: 10.1063/1.5140348
• 发表时间: 2020
• 期刊: Physics of Plasmas
• 影响因子: 2.2
• 作者: Seo, Byonghoon;Wongwaitayakornkul, Pakorn;Haw, Magnus A.;Marshall, Ryan S.;Li, Hui;Bellan, Paul M.
• 通讯作者: Bellan, Paul M.

Magnetic Rayleigh–Taylor Instability in an Experiment Simulating a Solar Loop

模拟太阳环实验中的磁瑞利泰勒不稳定性

• DOI: 10.3847/2041-8213/ab6b2d
• 发表时间: 2020
• 期刊: The Astrophysical Journal
• 作者: Zhang, Yang;Wongwaitayakornkul, Pakorn;Bellan, Paul M.
• 通讯作者: Bellan, Paul M.

Neutral-charged-particle Collisions as the Mechanism for Accretion Disk Angular Momentum Transport

中性带电粒子碰撞作为吸积盘角动量输运的机制

• DOI: 10.3847/1538-4357/ac62d5
• 发表时间: 2022
• 期刊: The Astrophysical Journal
• 作者: Zhang, Yang;Bellan, Paul M.
• 通讯作者: Bellan, Paul M.

The electron canonical battery effect in magnetic reconnection: Completion of the electron canonical vorticity framework

磁重联中的电子正则电池效应：电子正则涡度框架的完成

• DOI: 10.1063/1.5122225
• 发表时间: 2019
• 期刊: Physics of Plasmas
• 影响因子: 2.2
• 作者: Yoon, Young Dae;Bellan, Paul M.
• 通讯作者: Bellan, Paul M.

Caltech Lab Experiments and the Insights They Provide Into Solar Corona Phenomena

• DOI: 10.1029/2020ja028139
• 发表时间: 2020-08
• 期刊: Journal of Geophysical Research: Space Physics
• 作者: P. Bellan