MHD turbulence and the generation of large-scale fields in the Sun.

众所周知的11年太阳黑子周期是太阳磁场活动的一种表现。太阳黑子是太阳表面的冷暗斑，与强磁场有关。它们在一个周期开始时出现在中纬度地区，然后迁移到赤道。自世纪望远镜发明以来，太阳磁场活动一直被记录下来，使用代用数据可以将活动记录追溯到数千年前。解释太阳磁场的起源是太阳磁流体力学的基本问题。这个磁场是所有太阳磁场现象的基础，如太阳耀斑、日冕物质抛射和太阳风，并负责将日冕加热到如此高的温度。这些现象都可能对地球产生重大影响，造成严重的磁暴和对卫星的重大破坏，并可能对地球气候产生影响。这一提议旨在深入了解导致太阳磁场产生的物理过程。这是一个复杂的问题，涉及到极热等离子体中的湍流流体流动与流体内带电粒子运动产生的磁场之间的相互作用。一个悬而未决的问题是，在太阳内部存在的极端条件下，这样一个动荡的系统如何能产生一个连贯的系统现象，如大规模的11年太阳磁周期。由于不可能在计算机上模拟整个太阳，传统的方法是使用参数来模拟小尺度的行为。选择这些参数是为了在不考虑所涉及的物理过程细节的情况下拟合观测结果。在这里，我们建议使用湍流和磁场之间的相互作用的数值模拟来研究如何系统的大尺度行为可以出现。这些数值计算将在二维和三维空间进行，将使用最先进的计算方法，这些方法经过优化，可在功能强大的现代计算机上使用，这将使我们能够达到高度湍流和参数的极端值。这些模拟将使用利兹大学的并行计算设施进行。计算结果将进行比较和对比，在参数制度的分析进展是可能的。这种方法将使识别的适用范围的限制，适用于这种湍流现象的分析，也将产生一个过程，可以导致有序的行为出现不相干的湍流系统的理解。通过这种方式，我们建议提高我们的太阳磁周期的产生机制和太阳磁场的重要动力学的理解。

The well-known eleven-year sunspot cycle is a manifestation of solar magnetic activity. Sunspots are cool dark patches on the solar surface which are associated with strong magnetic fields. They appear at mid-latitudes at the start of a cycle and migrate to the equator. Solar magnetic activity has been recorded since the early 17th Century following the invention of the telescope and the activity record can be extended back thousands of years using proxy data. Explaining the origin of the sun's magnetic field is the fundamental problem of solar magnetohydrodynamics. This field underlies all solar magnetic phenomena such as solar flares, coronal mass ejections and the solar wind, and is responsible for heating the solar corona to such high temperatures. These phenomena may all have important terrestrial impacts, causing severe magnetic storms and major disruption to satellites, as well as having a possible impact on the terrestrial climate. This proposal is designed to give an insight into the physical processes that lead to the generation of the magnetic field in the Sun. This is a complicated problem that involves the interaction between the turbulent fluid flows in an extremely hot plasma and the magnetic field that is generated by motions of charged particles within the fluid. The outstanding question is how a coherent systematic phenomenon such as the large-scale eleven-year solar magnetic cycle can arise from such a turbulent system under such extreme conditions as exist in the interior of the Sun. As it is impossible to simulate the whole Sun on a computer, the traditional approach is to model the action of the small-scales using parameters. These are chosen in order to fit the observations without taking the details of the physical processes involved into account. Here we propose to use numerical simulations of the interaction between turbulent flows and magnetic field to investigate how systematic large-scale behaviour can emerge. These numerical computations, which will be carried out in two and three-dimensions, will use state-of-the-art computational methods optimised for use on powerful modern computers, which will enable us to reach high degrees of turbulence and extreme values of the parameters. These simulations will be carried out using the parallel computational facility at the University of Leeds. The computations will be compared and contrasted with the results of analysis in parameter regimes where analytical progress is possible. This approach will enable the identification of the limitations of the range of applicability of analysis as applied to such turbulent phenomena and will also yield an understanding of the processes that can lead to ordered behaviour emerging from incoherent turbulent systems. In this way we propose to enhance our understanding of the mechanisms for generation of the solar magnetic cycle and of the important dynamics of the solar magnetic field.