火星空间电流体系分布特征
发布时间：2018-11-23 20:03
【摘要】：本文在多成分单流体MHD模拟基础上,计算了火星空间大尺度电流体系,并对磁异常对火星空间电流的影响进行了分析。其结果表明,火星空间存在着弓激波电流、磁堆积区边界电流、电离层电流和磁尾中心电流片。磁异常对四种电流均有不同程度的影响。 火星空间大尺度电流分布的特点有,弓激波电流在弓激波曲面上均由北流向南,自成体系,电流方向垂直于行星际磁场方向,电流强度在弓激波顶区域较大。磁堆积区边界电流均由北向南流动形成两支电流,在向阳面与电离层电流构成回路,而在背阳面和磁尾中心电流片耦合形成完整的回路。磁尾中心电流片在近火星1.3RM内受火星电离层影响较大,会分离为两支或更多电流片耦合在一起。电离层电流强度是所有电流体系中最大的,平均电流强度都在100nA/m2以上,且向阳面电流强度均比背阳面大。 磁异常对四种电流有着不同的影响。磁异常的存在使弓激波电流曲率比没有磁异常时要大些,激波面的平均位置离火星也会更远一点。磁异常使向阳面磁堆积区边界电流强度增大了很多,电流流线形态也变得不太规律;背阳面磁堆积区边界电流的南北流入、流出源连线的位置同时发生了偏移,磁堆积区两瓣的电流半径也变得更大些。不过磁异常的影响使火星南北两极区的磁堆积区电流分布的高度变低了,形态也更规律些。磁异常使磁尾中心电流片的影响有限,使其与子午面存在着一定的夹角,在背阳面离火星中心1.8RM范围之内,近火表面磁尾中心电流片会有多条电流片耦合在一起。磁异常对电离层电流的影响较大,使火星电离层局部电流强度增强很大,尤其在南半球电流强度可达上万nA/m2,但整体上并没有改变向阳面和背阳面的电流强度分布差异的特点。磁异常也并没有改变电离层的电流整体由南极附近流向北极的趋势,不过使流线分布变得很复杂,部分区域变得非常杂乱,尤其在南半球电流强度较强处出现了打圈、褶皱等现象。
[Abstract]:Based on the multi-component single-fluid MHD simulation, the large scale current system of Mars space is calculated, and the influence of magnetic anomaly on the space current of Mars is analyzed. The results show that there are bow shock current, boundary current in magnetic accumulation region, ionospheric current and central current sheet in the space of Mars. Magnetic anomalies have different effects on the four kinds of currents. The characteristics of large scale current distribution in Mars space are as follows: the current of bow shock wave is from north to south on the surface of the bow shock wave, and the current direction is perpendicular to the interplanetary magnetic field, and the current intensity is larger in the area of the top of the bow shock wave. The boundary currents flow from north to south to form two currents in the magnetic stacking area, which form a circuit with the ionospheric current on the positive surface, and a complete circuit is formed on the back positive surface and the central current sheet of the magnetotail. The magnetotail central current sheet is strongly influenced by the Mars ionosphere in the near Mars 1.3RM and will be separated into two or more current sheets coupled together. The ionospheric current intensity is the largest in all current systems, the average current intensity is above 100nA/m2, and the positive current intensity is higher than that of the back positive current system. Magnetic anomalies have different effects on the four kinds of currents. Due to the existence of magnetic anomalies, the curvature of the bow shock current is larger than that without the magnetic anomaly, and the average position of the shock surface is farther away from Mars. Because of the magnetic anomaly, the boundary current intensity increases a lot and the current flow pattern becomes irregular. The position of the line of the outflow source is shifted simultaneously, and the current radius of the two lobes in the magnetic packing area becomes larger as well as the north and south inflow of the boundary current in the magnetic stacking area on the back positive surface. However, the effect of magnetic anomalies has reduced the height of the current distribution in the magnetic accumulation region in the north and south poles of Mars, and the pattern is more regular. The effect of magnetic anomaly on the central current sheet is limited and there is a certain angle between it and the meridional plane. Within the range of the back positive surface from the central 1.8RM of Mars, there will be a number of current sheets coupled together in the near surface of the magnetotail current sheet. The magnetic anomaly has a great influence on the ionospheric current, which increases the local current intensity of the Mars ionosphere, especially in the Southern Hemisphere, where the current intensity can reach tens of thousands of nA/m2,. But on the whole, it does not change the characteristics of the distribution of the current intensity toward the positive and the back. The magnetic anomalies have not changed the overall trend of the ionospheric current flowing from the South Pole to the North Pole, but the streamline distribution has become very complicated, and some areas have become very messy, especially in the southern hemisphere where the current intensity is relatively strong. Fold, etc.
【学位授予单位】：中国科学院研究生院（空间科学与应用研究中心）
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：P185.3
本文编号：2352558
[Abstract]:Based on the multi-component single-fluid MHD simulation, the large scale current system of Mars space is calculated, and the influence of magnetic anomaly on the space current of Mars is analyzed. The results show that there are bow shock current, boundary current in magnetic accumulation region, ionospheric current and central current sheet in the space of Mars. Magnetic anomalies have different effects on the four kinds of currents. The characteristics of large scale current distribution in Mars space are as follows: the current of bow shock wave is from north to south on the surface of the bow shock wave, and the current direction is perpendicular to the interplanetary magnetic field, and the current intensity is larger in the area of the top of the bow shock wave. The boundary currents flow from north to south to form two currents in the magnetic stacking area, which form a circuit with the ionospheric current on the positive surface, and a complete circuit is formed on the back positive surface and the central current sheet of the magnetotail. The magnetotail central current sheet is strongly influenced by the Mars ionosphere in the near Mars 1.3RM and will be separated into two or more current sheets coupled together. The ionospheric current intensity is the largest in all current systems, the average current intensity is above 100nA/m2, and the positive current intensity is higher than that of the back positive current system. Magnetic anomalies have different effects on the four kinds of currents. Due to the existence of magnetic anomalies, the curvature of the bow shock current is larger than that without the magnetic anomaly, and the average position of the shock surface is farther away from Mars. Because of the magnetic anomaly, the boundary current intensity increases a lot and the current flow pattern becomes irregular. The position of the line of the outflow source is shifted simultaneously, and the current radius of the two lobes in the magnetic packing area becomes larger as well as the north and south inflow of the boundary current in the magnetic stacking area on the back positive surface. However, the effect of magnetic anomalies has reduced the height of the current distribution in the magnetic accumulation region in the north and south poles of Mars, and the pattern is more regular. The effect of magnetic anomaly on the central current sheet is limited and there is a certain angle between it and the meridional plane. Within the range of the back positive surface from the central 1.8RM of Mars, there will be a number of current sheets coupled together in the near surface of the magnetotail current sheet. The magnetic anomaly has a great influence on the ionospheric current, which increases the local current intensity of the Mars ionosphere, especially in the Southern Hemisphere, where the current intensity can reach tens of thousands of nA/m2,. But on the whole, it does not change the characteristics of the distribution of the current intensity toward the positive and the back. The magnetic anomalies have not changed the overall trend of the ionospheric current flowing from the South Pole to the North Pole, but the streamline distribution has become very complicated, and some areas have become very messy, especially in the southern hemisphere where the current intensity is relatively strong. Fold, etc.
【学位授予单位】：中国科学院研究生院（空间科学与应用研究中心）
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：P185.3
【参考文献】
相关期刊论文 前1条
1 张艺腾;李磊;;火星空间磁场结构特征[J];空间科学学报;2009年03期
，本文编号：2352558
本文链接：https://www.wllwen.com/kejilunwen/tianwen/2352558.html
