Evolution of coronal magnetic fields

太阳磁场将太阳内部与光球层和日冕耦合，在那里它驱动加热过程和爆发现象。在日冕中，磁能是准静态地积累起来的，直到它远远超过储存在日冕中的能量。磁位形这种多余的能量部分地通过大的爆发现象间歇性地释放，例如日冕物质抛射、耀斑和爆发性耀斑，但也通过小的爆发现象释放，例如爆炸事件和纳米和微米耀斑，它们可能是加热日冕的核心。大多数对磁场矢量的测量都局限于光球层，因此磁场需要从光球层外推到日冕。在这个项目中，我们建议使用一个非线性的力自由的优化代码来计算三维日冕磁场的光球测量。日冕磁场的无力描述是合理的，因为低日冕和中日冕中的低等离子体的。该研究旨在调查活动区域的时间准静态演化，目的是深入了解耀斑和CME以及爆炸事件和微耀斑所需的条件。

The solar magnetic field couples the solar interior with the photosphere and corona where it drives heating processes and eruptive phenomena. In the corona the magnetic energy is quasi-statically built up until it exceeds by far the energy stored in a. potential magnetic configuration. This excess energy is intermittently released in parts by large eruptive phenomena, e.g. coronal mass ejections, flares and eruptive prominences, but also through small ones, such as explosive events and nano- and micro- flares which are probably central for heating the solar corona. Most measurements of the magnetic field vector are restricted to the photosphere, so that the magnetic field needs to be extrapolated from there into the corona. Within this project we propose to use a non-linear force-free optimization code to compute the 3D coronal magnetic field from photospheric measurements. A force-free description of the coronal magnetic field is justified due to the low ß plasma in the low and middle corona. The study aims to investigate the temporal quasi-static evolution of active regions with the aim of getting insights into the conditions required for flares and CMEs, as well as for explosive events and micro flares.