Quantifying magnetic fluxes and reconnection rates in complex fields

量化复杂场中的磁通量和重联率

• 批准号: ST/G002436/1
• 负责人: Gunnar Hornig
• 金额: $ 35.41万
• 依托单位: University of Dundee
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2009
• 资助国家: 英国
• 起止时间: 2009 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=ST%2FG002436%2F1
• 关键词: Quantifying; magnetic; fluxes; reconnection; rates; Quantifying; magnetic; fluxes; reconnection; rates

The Sun's atmosphere, as well as the atmospheres of most stars, consists of a hot plasma which is structured by a complex magnetic field. At random intervals the structure of this magnetic field undergoes a sudden local change, a so-called magnetic reconnection event, which can trigger minor or major outbreaks of plasma. These outbreaks heat the atmosphere and release plasma from the solar atmosphere into the interplanetary space. It is suspected that these reconnection processes occur not in the form of individual events but more in the form of an avalanche, where an initial major event triggers a series of smaller reconnection events. However, we are unable to detect these with our current observational methods. This proposal aims to develop the theoretical tools to answer the fundamental question of whether reconnection occurs in form of a singular event or as an avalanche. One of the main goals is to identify the characteristic signature of magnetic reconnection. This 'fingerprint' of reconnection is given by a specific change in the structure of the field and can be quantified in terms of magnetic flux. In order to detect this fingerprint of reconnection in the observed magnetic fields on the Sun we have to analyse these also with respect to their structure and the magnetic fluxes involved. For this we must define certain measures, so-called topological fluxes, and the proposal aims to define these measures and provide algorithms for finding them in arbitrary magnetic fields. Eventually these will allow us to answer the main question as to whether magnetic reconnection occurs as an individual event or an avalanche. An answer to this question is not only of great interest to solar physics but also to other fields where similar plasmas are found such as in the atmospheres of other stars, in the turbulent plasma in accretion disks and the plasma in fusion devices.

太阳的大气以及大多数恒星的气氛包括由复杂磁场结构的热等离子体。在随机的间隔中，该磁场的结构发生了突然的局部变化，即所谓的磁重新连接事件，该事件可能会触发血浆的次要或重大暴发。这些爆发会加热大气并将血浆从太阳大气中释放到行星际空间中。人们怀疑这些重新连接过程不是出于单个事件的形式出现，而是以雪崩形式出现，其中最初的主要事件会触发一系列较小的重新连接事件。但是，我们无法通过当前的观察方法检测到这些。该建议旨在开发理论工具，以回答重新连接是以单一事件的形式或雪崩形式发生的基本问题。主要目标之一是确定磁重新连接的特征标志。重新连接的“指纹”由场结构的特定变化给出，可以用磁通量来量化。为了检测在太阳上观察到的磁场中重新连接的指纹，我们还必须针对它们的结构和所涉及的磁通量进行分析。为此，我们必须定义某些措施，所谓的拓扑通量，该提案旨在定义这些度量并提供算法以在任意磁场中找到它们。最终，这些将使我们能够回答有关磁重新连接是作为单个事件还是雪崩的主要问题。这个问题的一个答案不仅是太阳能物理学的极大兴趣，而且对其他类似的等离子体的兴趣，例如在其他恒星的大气中，积聚磁盘中的湍流等离子体和融合设备中的等离子体。