Explosive energy release in solar and space plasmas

磁约束等离子体中的爆炸能量释放是一个普遍的过程，从太阳系中存在的天然等离子体到托卡马克等聚变反应堆。从恒星大气层，包括我们自己的太阳，到彗星尾巴和我们自己的近地空间，这些环境在几分钟到几天的时间尺度上存储磁能，然后在更短的时间尺度上爆炸性地释放并转化为等离子体动能。这种局部过程对磁场的重新配置和粒子的能量化具有大规模的影响。储存的能量迅速转化为快速运输的磁通束远离现场，各种粒子加速过程和电磁波的产生。是什么过程或过程导致这种爆炸性的能量释放在每个局部等离子体环境中仍然是激烈的争论。我们最近发现，在地球环境中有一个可重复的爆炸能量释放的光学特征（称为磁层亚暴; Kalmoni等人，Nature Communications，2018）。有了这个结果，我们已经能够确定不稳定的电磁波与这种能量释放密不可分，解决了一个60年的科学问题的关键部分，即是什么导致了近地磁尾的爆炸性能量释放。太阳耀斑，而代表一个相当不同的参数制度，地球的磁层，但显示定性相似的可重复的光学签名。这个博士学位的目标是建立在Kalmoni等人（2018）所做的工作的基础上，研究不稳定的电磁波是否也在产生太阳耀斑爆炸能量释放期间观察到的特征中发挥作用。该学生将利用现有软件并在这一研究框架的基础上，将为磁层亚暴分析开发的技术应用于从地面和天基平台对太阳耀斑进行多波长观测，以确定波的存在并将其特征与磁层亚暴中观测到的特征进行比较。

Explosive energy release in magnetically confined plasmas is a universal process, from the natural plasmas that exist in the solar system to fusion reactors such as tokamaks. From stellar atmospheres, including our own Sun, to comet tails and our own near-Earth space, these environments store magnetic energy over timescales ranging between minutes and days, which is then explosively released over far shorter timescales and converted into plasma kinetic energy. This local process has large-scale consequences for the reconfiguring the magnetic field and particle energisation. Stored energy is quickly converted into the rapid transport of bundles of magnetic flux away from the site, a variety of particle acceleration processes and the generation of electromagnetic waves. What process or processes cause this explosive energy release across each local plasma environment is still hotly debated. We have recently discovered that there is a repeatable optical signature of the explosive energy release within Earth's environment (termed a magnetospheric substorm; Kalmoni et al., Nature Communications, 2018). With this result, we have been able to identify that unstable electromagnetic waves are inextricably linked to this energy release, solving a crucial part of a 60 year old science question of what causes this explosive energy release in the near-Earth magnetotail. Solar flares, while representing a rather different parameter regime to the Earth's magnetosphere, nevertheless display qualitatively similar repeatable optical signatures. The goal of this PhD is to build on the work done by Kalmoni et al. (2018) to investigate whether unstable electromagnetic waves are also playing a role in generating the signatures observed during the explosive energy release of solar flares. Using existing software and building upon this research framework, the student will apply the techniques developed for magnetospheric sub-storm analysis to multi-wavelength observations of solar flares, from ground and space-based platforms, with a view to determining the presence of waves and comparing their characteristics with those observed in magnetospheric sub-storms.