Dynamics in solar prominences - connecting from small to large scale

最近的太空太阳任务，日本的日野号任务和美国宇航局的太阳动力学观测站（SDO）任务，提供了静止日珥（冷却- 8000K -部分电离等离子体云漂浮在1MK日冕）的惊人观测结果，揭示了它们是高度动态的现象，其中磁化等离子体的基本过程不断显示。举一个具体的例子，最令人兴奋的发现之一是磁瑞利-泰勒不稳定性，当致密流体在轻流体之上时，边界受到干扰，导致上升和下降羽流的形成，这种不稳定性就会增加。由于驱动这些动力学的基本物理学，许多与日珥有关的关键问题的答案——即是什么决定了它们何时爆发，不稳定性如何在复杂的日珥环境中增长，磁重联（释放能量的磁场连通性的变化）如何在部分电离的日珥等离子体中工作，日珥中不同尺度之间的联系是什么——很可能隐藏在它们之中。然而，日珥系统的巨大复杂性意味着我们仍然需要了解这些被称为日珥的美丽结构。最近在计算能力、理论建模和新发射的美国宇航局卫星界面区域成像光谱仪（IRIS）方面的进展-具有高灵敏度和分辨率-意味着我们现在有了解决与这个复杂系统有关的问题的工具。使用最先进的代码，可以同时解决部分电离等离子体系统中中性和离子的动力学，可以正确地跟踪组成日珥等离子体的两种流体之间的相互作用。控制日珥系统的基础物理模拟将用这种部分电离的等离子体代码进行，并将结果与观测数据进行比较和对比，以使理论和观测相互指导。通过使用所有可用工具的反馈方法，我们可以对突出系统有一个新的、令人兴奋的理解。提出的工作有几个关键目标将被研究：1)MHD不稳定性（特别是磁瑞利-泰勒不稳定性）如何在静止日珥中形成。2)小空间和时间尺度上的不稳定性对日珥系统在更长的时间尺度和更大的空间尺度上的影响，这些过程的观测特征是什么，它们与日珥喷发有什么关系。3)在许多可观测尺度上，控制部分电离日珥物质中磁场重联的基本物理是什么？我们如何将观测到的动态现象与日珥系统的复杂物理联系起来？这项研究将在剑桥大学应用数学和理论物理系（DAMTP）进行。在这个项目中，我将从理论和观测的角度研究观测到的日珥动力学的广泛范围。因此，使用广泛的技术，从日珥不稳定性形成的大规模数值模拟到太阳等离子体发射的光谱线分析，以确定日珥中的等离子体运动，将是必要的。DAMTP的资深员工在我学习所需的各个领域都有丰富的经验。Drs。Helen Mason和G. Del Zanna是太阳光谱观测领域的世界领导者。M. Proctor， J. Papaloizou和G. Ogilvie在通过大规模数值模拟研究天体物理系统方面经验丰富。所有这些结合在一起，使DAMTP成为我获得工作所需的全部支持的完美场所。

Recent space based solar missions, the Japanese Hinode mission and the NASA Solar Dynamics Observatory (SDO) mission, have provided breathtaking observations of quiescent prominences (cool - 8000K - clouds of partially ionised plasma floating in the 1MK solar corona) revealing them to be highly dynamic phenomena where the fundamental process of a magnetised plasma are on constant display. To provide a specific example, one of the most exciting discoveries is that of the magnetic Rayleigh-Taylor instability, an instability that grows when a dense fluid is above a light fluid and the boundary is perturbed resulting in the formation of rising and falling plumes. Due to the fundamental physics that drive these dynamics, the answers of many of the key questions relating to prominences - i.e. what determines when they erupt, how do instabilities grow in the complex prominence environment, how does magnetic reconnection (the change in connectivity of a magnetic field that releases energy) work in the partially ionised prominence plasma, what are the connections between the different scales in prominences - are likely to be hidden within them. However, the great complexity if the prominence system has meant that we are still to understand these beautiful structures known as prominences.Recent advances in computational power, theoretical modelling and the launch of the new NASA satellite the Interface Region Imaging Spectrograph (IRIS) - with its high sensitivity and resolution - mean that we now have the tools to tackle the problems relating to this complex system. Using a state-of-the-art code which simultaneously solves the dynamics of the neutrals and the ions in a partially ionised plasma system the interaction between the two fluids that make up the prominence plasma can be correctly tracked. Simulations of the fundamental physics that control the prominence system will be performed with this partially ionised plasma code, with the results compared and contrasted to the observational data to let theory and observations guide each other. Through this feedback approach employing all the tools that are available to use, we can head towards a new and exciting understanding to the prominence system.The proposed work has a number of key aims that will be investigated:1) How do MHD instabilities (in particular the magnetic Rayleigh-Taylor instability) form in quiescent prominences.2) How does the presence of instabilities on small spatial and temporal scales effect the prominence system on longer timescales and larger spatial scales, what are the observational signatures of these processes and how do they relate to prominence eruptions.3) What are the basic physics that controls the reconnection of magnetic fields in the partially ionised prominence material across the many observable scales.4) How can we connect between the dynamic phenomena observed and the complex physics of the prominence system. This research would take place at the Department of Applied Mathematics and Theoretical Physics (DAMTP), University of Cambridge. In this project, I will investigate the wide range of observed prominence dynamics from both a theoretical and observational perspective. Therefore, the use of a wide range of techniques, from large-scale numerical simulations of the formation of instabilities in a prominence to the analysis of the spectral lines emitted by solar plasma to determine the plasma motion in the prominence, will be necessary. The senior staff at DAMTP have great experience in a wide range of areas required for my study. Drs. Helen Mason and G. Del Zanna are world leaders in the field of solar spectral observations and Profs. M. Proctor, J. Papaloizou and G. Ogilvie are greatly experienced in the study of astrophysical systems through large-scale numerical simulations. All these combine to make DAMTP the perfect place to be to get the full support necessary for my work.