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Magnetic Reconnection in High Definition

高清磁重联

基本信息

批准号：
ST/L002809/1
负责人：
Robert Fear
金额：
$ 31.69万
依托单位：
University of Southampton
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2014
资助国家：
英国
起止时间：
2014 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=ST%2FL002809%2F1
关键词：
Magnetic Reconnection Definition

项目摘要

The region of space around the Earth is highly dynamic, driven by a fundamental physical process called magnetic reconnection. Reconnection occurs in hot gases called plasmas. When two plasmas come into contact, the magnetic fields in the two regions can become interconnected, causing the release of large amounts of energy. Reconnection occurs throughout the Universe; it is responsible for solar activity, it occurs in various astrophysical bodies and in laboratory plasmas (such as the fuel in experimental fusion reactors). However, the range and quality of instrumentation available to observe reconnection in Earth's environment makes this the best place to study this process; this is also the environment in which reconnection has the most impact on our day-to-day life, as the dynamics that are driven by reconnection have negative effects on modern day technology (space weather). For example, geomagnetic storms are driven by reconnection and cause damage to infrastructure on the ground; they also cause variations in intensity of the radiation belts which can harm satellites. Earth's auroras are also ultimately driven by the reconnection process.Reconnection at Earth occurs at the interface between two plasmas: the solar wind, which flows from the Sun to the outer reaches of the Solar System, and the magnetosphere, which is a cavity in the solar wind that is carved out by the Earth's magnetic field. These two plasmas have associated magnetic fields: the interplanetary magnetic field (IMF) and terrestrial magnetic field respectively. Reconnection can occur between the IMF and the terrestrial field at the interface between the magnetosphere and solar wind, which is called the magnetopause - it is reconnection at this interface that transfers energy and momentum from the solar wind into the magnetosphere and provides the ultimate driver for all magnetospheric dynamics. Here, reconnection occurs both in steady state and in bursts called flux transfer events (FTEs). Reconnection similarly controls the dynamics, to greater or lesser degrees, of most magnetised planets in the Solar System, and hence it is likely to be a significant process at most magnetised exoplanets too.In October 2014, NASA will launch a constellation of four spacecraft called the Magnetospheric Multiscale (MMS) mission, which will provide observations of the plasma environment in the Earth's magnetosphere at temporal resolutions that are far greater than previous missions. Most of the research effort in the MMS community is likely to be directed towards understanding the microphysics of reconnection, whilst the work outlined in the fellowship programme associated with this proposal will be resolving outstanding issues relating to the global scale contribution of bursty reconnection (FTEs) using data from previous missions. Here, we propose the use of the instrumentation provided by MMS to obtain a much greater understanding of FTEs on the mesoscale, which separates these two extremes (micro- and global scales). Hence it will complement both the study of the global-scale effects that is outlined in the fellowship programme and the research currently planned by the MMS team.The objective of this proposal is to test competing mechanisms for the manner in which bursty reconnection occurs at the Earth's magnetopause. This is necessary for the verification of global simulations of magnetospheric dynamics, but it will also inform our understanding of the underlying nature of reconnection, which is often time-varying (for reasons that are unclear). This will be done by applying a range of techniques that have individually been tested, but not combined; their separate application has led to a patchy picture with results that at times appear to conflict. By applying these methods together to a common data set derived from novel high resolution instrumentation, we will gain a deeper understanding of the manner in which this fundamental physical process occurs.

地球周围的空间区域是高度动态的，由一种称为磁重联的基本物理过程驱动。重联发生在被称为等离子体的高温气体中。当两个等离子体接触时，两个区域的磁场可以相互连接，导致大量能量的释放。重新连接发生在整个宇宙；它负责太阳活动，它发生在各种天体物理体和实验室等离子体中（如实验聚变反应堆中的燃料）。然而，可用于观测地球环境中重联的仪器的范围和质量使这里成为研究这一过程的最佳地点；这也是重新连接对我们日常生活影响最大的环境，因为由重新连接驱动的动力对现代技术（太空天气）有负面影响。例如，地磁风暴是由重联驱动的，会对地面基础设施造成破坏；它们还会引起辐射带强度的变化，从而损害卫星。地球的极光最终也是由重联过程驱动的。地球上的重联发生在两个等离子体之间的界面上：太阳风（从太阳流向太阳系外围）和磁层（太阳风中的一个空腔，由地球磁场雕刻而成）。这两个等离子体有相关的磁场：行星际磁场（IMF）和地球磁场分别。在磁层和太阳风之间的界面上，国际货币基金组织和地球磁场之间可能发生重联，这被称为磁层顶——正是在这个界面上的重联将能量和动量从太阳风转移到磁层，并为所有磁层动力学提供了最终的驱动力。在这里，重连接既发生在稳态中，也发生在称为通量转移事件（fte）的突发中。重联同样或多或少地控制着太阳系中大多数磁化行星的动力学，因此它可能也是大多数磁化系外行星的一个重要过程。2014年10月，美国宇航局将发射一个由四个航天器组成的星座，称为磁层多尺度（MMS）任务，该任务将以远高于以往任务的时间分辨率提供对地球磁层等离子体环境的观测。MMS社区的大部分研究工作可能都是为了理解重连的微观物理学，而与本提案相关的奖学金计划中概述的工作将利用以前任务的数据解决与全球范围内突发重连（fte）贡献相关的突出问题。在这里，我们建议使用MMS提供的仪器来更好地了解中尺度的fte，中尺度将这两个极端（微观和全球尺度）分开。因此，它将补充研究金计划中概述的全球规模效应研究和MMS团队目前计划的研究。这一提议的目的是测试在地球磁层顶发生突然重联的方式的竞争机制。这对于验证磁层动力学的全球模拟是必要的，但它也将告知我们对重联的潜在本质的理解，重联通常是时变的（原因尚不清楚）。这将通过应用一系列技术来实现，这些技术已经单独测试过，但没有组合起来；它们各自的应用导致了一幅参差不齐的画面，结果有时似乎相互冲突。通过将这些方法一起应用于来自新型高分辨率仪器的公共数据集，我们将更深入地了解这一基本物理过程发生的方式。