Turbulent Heating of Space Plasmas

空间等离子体的湍流加热

• 批准号: ST/N003748/1
• 负责人: Christopher Chen
• 金额: $ 64.64万
• 依托单位: Imperial College London
• 依托单位国家: 英国
• 项目类别: Fellowship
• 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=ST%2FN003748%2F1
• 关键词: Turbulent; Heating; Space; Plasmas

Plasma, the state of matter formed when a gas is heated to sufficiently high temperatures, is by far the dominant form of ordinary matter in the universe. How this plasma gets to be so hot, however, is currently one of the major mysteries in space and astrophysics. For example, the solar corona, the plasma atmosphere of the Sun, is hundreds of times hotter than the Sun's surface, but the reason for this has not yet been established. Understanding this heating is important for determining the origin of the solar wind, the continuous fast stream of plasma emitted from the Sun due to the high temperature in the corona. Furthermore, the solar wind itself is observed to undergo continuous heating as it expands to fill the solar system.The solar wind and solar corona, as well as most other astrophysical plasmas, are turbulent, meaning that they display complex chaotic motions at a broad range of scales. These motions are a possible source of energy for the observed heating, but exactly how this turbulence leads to heating remains to be understood, due to the previous lack of high resolution in situ measurements. In the next few years, a series of new spacecraft (DSCOVR, Solar Probe Plus, Solar Orbiter) will fly through the solar wind, measuring its properties, such as density, velocity, temperature, and electromagnetic fields, in far greater resolution than has ever been achieved before. This offers a unique opportunity to study turbulent heating, since for the first time we will be able to probe the plasma at the scales at which the heating is thought to occur.In my proposed research I will use this newly available data to answer some of the key questions about how turbulent energy leads to the heating of the solar wind and astrophysical plasmas in general. I will do this by looking for the characteristic signatures of the possible heating mechanisms in the measured solar wind particles, determining how the heating is distributed throughout the plasma in relation to the structures generated by the turbulence, and measuring how different types of particle in the solar wind are heated differently. By analysing data from Solar Probe Plus and Solar Orbiter, which will travel far closer to the Sun than ever before, I will investigate, in the later years of the project, how turbulent heating operates in different space environments and how the solar wind is heated close to its origin. This information about the dependence on plasma conditions will allow the results to be applied to other astrophysical plasmas in which heating is poorly understood, such as accretion disks and galaxy clusters. The research will be carried out at Imperial College London, in collaboration with colleagues in Europe and the USA.Although the proposed research is fundamental in nature, the results are potentially important for several applications, for example, space weather and fusion power. Space weather is a term for the changes in the space environment around Earth, which can have a significant impact on society at large, for example, damaging commercial satellites, disrupting flights, and interfering with electrical systems on the ground. Understanding the variability of the solar wind due to turbulence will help contribute to more accurate space weather predictions. Fusion power uses plasmas to generate sustainable clean energy, but is limited by the power needed to heat the plasma, and the difficulty in confining it due to turbulence. By investigating turbulence in space and determining how plasmas are naturally heated in the universe, this knowledge can be transferred to the lab to help achieve the goal of commercial fusion power.

等离子体是气体被加热到足够高的温度时形成的物质状态，是迄今为止宇宙中普通物质的主要形式。然而，等离子体如何变得如此热是目前太空和天体物理学的主要谜团之一。例如，日冕，即太阳的等离子体大气，比太阳表面热数百倍，但其原因尚未确定。了解这种加热对于确定太阳风的起源非常重要，太阳风是由于日冕高温而从太阳发出的连续快速等离子体流。此外，据观察，太阳风本身在膨胀填充太阳系时会经历持续加热。太阳风和日冕以及大多数其他天体物理等离子体都是湍流，这意味着它们在大范围内表现出复杂的混沌运动的秤。这些运动是观测到的加热的可能能量来源，但由于之前缺乏高分辨率的原位测量，这种湍流到底如何导致加热仍有待了解。在接下来的几年中，一系列新型航天器（DSCOVR、Solar Probe Plus、Solar Orbiter）将飞越太阳风，以比现有技术更高的分辨率测量其特性，例如密度、速度、温度和电磁场。以前曾经实现过。这为研究湍流加热提供了一个独特的机会，因为我们第一次能够在被认为发生加热的尺度上探测等离子体。在我提出的研究中，我将使用这些新的可用数据来回答一些问题关于湍流能量如何导致太阳风和天体物理等离子体加热的关键问题。为此，我将寻找所测量的太阳风粒子中可能的加热机制的特征特征，确定热量如何分布在整个等离子体中与湍流产生的结构相关，并测量不同类型的粒子在等离子体中的分布情况。太阳风的加热方式不同。通过分析来自 Solar Probe Plus 和 Solar Orbiter 的数据（它们将比以往任何时候都更接近太阳），我将在项目的后期研究湍流加热如何在不同的空间环境中运行以及太阳风如何被加热接近它的原点。有关等离子体条件依赖性的信息将使结果能够应用于对加热知之甚少的其他天体物理等离子体，例如吸积盘和星系团。该研究将在伦敦帝国理工学院与欧洲和美国的同事合作进行。虽然拟议的研究本质上是基础性的，但其结果对于多种应用具有潜在的重要意义，例如空间天气和聚变能。空间天气是地球周围空间环境变化的一个术语，它可能对整个社会产生重大影响，例如损坏商业卫星、扰乱航班以及干扰地面电力系统。了解太阳风因湍流而产生的变化将有助于更准确的空间天气预报。聚变能源使用等离子体产生可持续的清洁能源，但受到加热等离子体所需的功率以及由于湍流而难以限制等离子体的限制。通过研究太空中的湍流并确定等离子体在宇宙中如何自然加热，这些知识可以转移到实验室，以帮助实现商业聚变能源的目标。

项目成果

Arbitrary-order Hilbert Spectral Analysis and Intermittency in Solar Wind Density Fluctuations

任意阶希尔伯特谱分析和太阳风密度涨落的间歇性

• DOI: http://dx.10.3847/1538-4357/aabcc2
• 发表时间: 2018
• 期刊: The Astrophysical Journal
• 作者: Carbone F

Numerical Study of Inertial Kinetic-Alfvén Turbulence

惯性运动阿尔文湍流的数值研究

• DOI: 10.3847/1538-4357/aaf288
• 发表时间: 2019-01-14
• 期刊: The Astrophysical Journal
• 作者: V. Roytershteyn;S. Boldyrev;G. Delzanno;C. Chen;D. Grošelj;N. Loureiro
• 通讯作者: N. Loureiro

On the 1/ f Spectrum in the Solar Wind and Its Connection with Magnetic Compressibility

太阳风的 1/ f 谱及其与磁压缩性的关系

• DOI: http://dx.10.3847/2041-8213/aaf573
• 发表时间: 2018
• 期刊: The Astrophysical Journal
• 作者: Matteini L

Three-dimensional simulations of solar wind turbulence with the hybrid code CAMELIA

使用混合代码 CAMELIA 进行太阳风湍流的三维模拟

• DOI: http://dx.10.1088/1742-6596/1031/1/012002
• 发表时间: 2018
• 期刊: Conference Series
• 作者: Franci L

TESTING THE EFFECTS OF EXPANSION ON SOLAR WIND TURBULENCE

测试膨胀对太阳风湍流的影响

• DOI: 10.3847/2041-8205/832/1/l16
• 发表时间: 2016-11-16
• 期刊: The Astrophysical Journal Letters
• 作者: D. Vech;C. Chen
• 通讯作者: C. Chen