火星电流系及其磁场

发布时间：2018-03-22 00:30

本文选题：火星　切入点：电流　出处：《中国科学技术大学》2011年博士论文　论文类型：学位论文

【摘要】：在太阳系八大行星中,除金星和火星之外,其它行星都有比较强的内禀磁场。鉴于各个行星自身的差异性,特别是它们的磁场拓扑结构,因而它们与太阳风作用的性质有所不同,各自形成的磁层结构以及产生的磁层现象也不尽相同。火星被认为是太阳系中自然环境最接近地球的行星,因此越来越为人类所关注。对火星磁场的探测与研究已经成为空间物理领域里的热门课题之一。本文利用火星具有电离层而无内禀磁场的特点以及它与太阳风作用的性质,从电流的角度出发,建立火星感应磁场模型,对火星感应磁场产生的原因、分布情况进行研究。同时,根据探测器所观测到的火星极光图片,建立极光区地壳磁场模型,得到了磁力线拓扑结构并且讨论了磁异常的成因。本文的主要工作以及得到的结果概括如下: 由于火星没有显著的内禀磁场,它与太阳风作用的方式与地球有很大的差异。太阳风直接与火星电离层、大气层发生相互作用,导致了火星电离层上出现感应电流。在第二章中,根据卫星所观测到的火星磁场分布特征以及电流始终包络磁力线这一特性,构建了火星磁层电流体系模型。在模型中,火星磁层顶电流,电离层电流以及磁尾中性片电流构成了火星磁层电流体系。根据电流连续性的条件,这三种电流满足一定的关系:磁层顶上通过的总电流是电离层上通过的总电流与磁尾中性片通过的总电流之和。本文分别讨论了火星磁层电流体系分布的二维近似模型和三维分布模型。第三章以火星磁层电流体系模型为基础,分别构建了火星感应磁场二维近似模型和三维模型。在模型中,火星磁层顶电流,电离层电流以及磁尾中性片电流产生的磁场与太阳风磁场一起构成了火星周围的磁场分布。根据毕奥-萨伐尔定理和利用磁力线跟踪程序,得到了火星赤道面以及与赤道面平行的其它平面内的磁场分布。计算结果表明,根据模型得到的磁场分布与卫星观测到的结果以及他人研究结果符合的较好。火星周围的磁场分布与具有内禀磁场的行星不同,其磁力线披挂在火星周围,在磁尾形成一个开放的结构。同时计算结果还表明,不同平面内磁力线拓扑结构既有类似的地方,又存在较大的差异性。与赤道面平行且越近的平面内,磁力线的“拖拽”程度越明显,这主要由于火星电离层对不同的区域内行星际磁场的阻碍程度不同。与具有较强内禀磁场的行星两极上出现的极光不同,火星极光主要发生在南半球地壳磁场异常的区域,并且极光分布特征与其它行星上的极光也有所区别。第四章在“火星全球勘探者”和“火星快车”的最近观测结果基础上,从等效电流的角度出发,建立了火星极光区地壳磁场模型,得到了火星地壳磁异常区的磁场拓扑结构。基于极光发生于磁力线汇聚的地方,利用模型得到的磁场拓扑结构,能够复原出所观测到的火星极光图像。同时,根据火星极光弧的宽度比较窄这一显著分布特征,本文对火星地壳磁异常的起因进行了讨论。
[Abstract]:In the eight planets in the solar system, in addition to Venus and Mars, the other planets have their intrinsic magnetic fields. In view of the differences between the planets themselves, especially their magnetic field topologies, the nature and function of the solar wind are different, their respective magnetic layer structure formed and the magnetic layer phenomenon not all the same. Mars is considered the solar system in the natural environment of the planet closest to the earth, so more and more concern for the human. The exploration and research of Martian magnetic field has become one of the hot topics in the field of space physics.
The Mars ionosphere has no intrinsic characteristics and magnetic field and the solar wind properties, from the perspective of the current establishment of Martian induced magnetic field model, the reason of Martian induced magnetic field, study the distribution situation. At the same time, according to the probe observed Martian Aurora image, establish the auroral crustal magnetic field model of magnetic field line topology obtained and the causes of magnetic anomalies are discussed. The main work of this paper and the results obtained are summarized as follows:
Because Mars has no intrinsic magnetic field significantly, there is a great difference between it and the solar wind with the earth. The solar wind directly with the Martian ionosphere, atmosphere interaction, leads to the appearance of the induced current on the ionosphere. In the second chapter, according to the satellite observed in the Martian magnetic field distribution and the characteristics of current always build envelope lines, Mars magnetospheric current system model. In the model, the Martian magnetopause current, ionospheric current and the current sheet in magnetotailform the Martian magnetospheric current system. According to the continuity of the current conditions, the three current the total current of the magnetopause is through the ionospheric total current and total current through the magnetotail neutral sheet. And this paper discusses the approximate model and three-dimensional distribution model of two-dimensional Martian magnetospheric current system distribution.
The third chapter is based on the current system model of Martian magnetosphere, respectively. The approximate model and three-dimensional model of Martian induced magnetic field. In the two-dimensional model, the Martian magnetopause current, ionospheric current and the current sheet in magnetotail magnetic field generated by the magnetic field and the solar wind together constitute the distribution of magnetic field around Mars. According to Biot Savart using theorem and magnetic tracking program, the Martian equatorial plane and the equatorial plane parallel to the other of the magnetic field distribution. The calculation results show that the distribution of magnetic field according to the observation model and the satellite to the results and others study results. The distribution of magnetic field around Mars is different with the intrinsic magnetic field of the planet. Lines drape around Mars, forming an open structure in the magnetotail. Results also show that the topologies of magnetic field in different planes is similar to There is a great difference between the two sides. The more the parallel and nearer the plane of the equator, the more obvious the magnetic drag line is. This is mainly due to the different degree of obstruction of the Mars ionosphere to the interplanetary magnetic field in different regions.
Different and has strong intrinsic magnetic poles on the planet Mars Aurora, Aurora occurs mainly in the southern hemisphere region of crustal magnetic anomalies, and Aurora distribution and other planets auroras are different. In the fourth chapter, "the recent observations of Mars Global Surveyor" and "Mars Express", starting from the angle of equivalent current, established the Martian Aurora crustal magnetic field model, the magnetic field topology of Martian crustal magnetic anomalies are obtained. Aurora occurs where lines converge on the results by using the model of magnetic field topology, to reconstruct the Martian Aurora images observed. At the same time, according to the width of the Martian Aurora arc the obvious feature of the narrow, this paper discussed the causes of the Martian crustal magnetic anomalies.

【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2011
【分类号】：P185.3

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