Field-Aligned Current Systems at Mercury

水星是距离太阳最近的轨道行星，因此被密集且变化很大的太阳风包裹着。太阳风与相对较弱的内部磁场的相互作用产生了一个形状类似于地球磁层但大小要小得多的磁层。因此，对地球有效的磁场和电流系统的多种模型可以在一定的约束下适用于水星。一个限制因素是明显缺乏可测量的第二区场向电流(R2-FAC)系统。在这个项目中，我们将用我们的混合模拟代码AI.K.E.F.来解决这个问题，即R2-FAC是否存在于水星。Herean磁层的电流模型将采用多种方法加以扩展：1.考虑重离子外圈(巨大的离子陀螺半径可能携带所需的闭合电流)；2.纳入多壳层电导率模型(预计会有行星内流)；3.考虑次阿尔夫尼克太阳风(不同的电流系)。通过这些方法，我们将改进现有的平均磁层模型。该模型将与重新分析的信使号现场磁场数据进行比较。了解潜在的R2-FAC的来源将提高我们对独特的赫门磁层的了解。此外，改进的水星模型将极大地帮助对即将到来的欧空局-日本宇宙航空研究开发机构的比普科伦坡飞行任务进行科学规划。

Planet Mercury is the closest orbiting planet around the sun and is therefore embedded inan intensive and highly varying solar wind. The interaction of the solar wind withthe relatively weak interior magnetic field yields a magnetosphere that is similar in shape but much smaller in size to the magnetosphere of the Earth. Hence, multiple models for the magnetic field and current systems that are valid for Earth can be applied to Mercury with certain restraints. One restraint is the apparent lack of a measured Region 2 field-aligned current (R2-FAC) system. In this project, we will address this question, whether the R2-FAC exist at Mercury with our hybrid simulation code A.I.K.E.F. . The current model of the Hermean magnetosphere will be expanded using multiple approaches: 1. Consideration of a heavy ion exosphere (huge ion gyro radii might carry needed closure currents), 2. Inclusion of a multiple shell conductivity model (inner planetary currents are expected), 3. Consideration of a sub-alfvénic solar wind (different current systems). With these approaches, we will improve the existing average magnetosphere model. The model will be compared against reanalyzed in-situ MESSENGER magnetic field data. Knowing about the sources of potential R2-FAC will improve our knowledge about the unique Hermean magnetosphere. Furthermore, the improved Mercury model will greatly aid in the scientific planning of the upcoming ESA-JAXA BepiColombo mission.