电子反射法探测月表磁异常的数值模拟

发布时间：2018-03-10 06:12

本文选题：月表磁异常　切入点：月表电场　出处：《中国科学院研究生院（空间科学与应用研究中心）》2011年博士论文　论文类型：学位论文

【摘要】：月球探测是目前深空探测中的热点之一。而月表磁场探测是其中基本而又关键的内容。本文首先介绍了月表磁异常及月表电场,并论述了月表磁异常探测的意义和现状,还介绍了利用反射的太阳风电子探测月表磁异常的原理、方法等。在此基础上,本文着重介绍了用电子反射法探测月表磁异常的数值模拟结果。本文采用单粒子轨道法,通过对不同磁场条件下电子反射率和反射分布的模拟,寻找区分月表不同磁场的方法和精度。本文还讨论月表电场,及其对电子反射法的影响和修正处理。通过数值模拟,本文研究分析了不同电磁场条件下的电子反射率变化和反射分布变化,结合理论公式探讨变化原因,并证明可以通过电子反射法反推月表电场,以及通过公式消除电场对电子反射法的影响。本文的主要结论是,太阳风电子在月表的反射会随月表电磁场条件的变化而变化,而且磁场与电场各自的变化引起的太阳风电子运动轨迹变化都是可区分的:通过反射分布可以定性推断月面是否存在磁异常,由电子反射率结合卫星处磁场强度可以进一步定量计算月表的磁场强度。磁场影响只受卫星轨道处磁场强度与磁异常磁场强度的比值,电场的影响区域则是全方位的。月表的充电情况与光照、月表性质、等离子体环境等存在复杂关系,在向阳面月表通常带正电,而阴影处月表通常会带负电,并且在月表和卫星之间会形成电势差。这个电势差,会对电子反射法测量月表磁异常的工作带来深刻的影响。本文通过模拟分析发现,对于同一能量的电子,月表带正电时,电场强度越大,发生反射的临界角变越大,被反射的越少;月表带负电时,电场强度越大,发生反射的临界角变越小,反射也越多;对于不同能量的电子,在相同电场条件下,能量越高,临界角变化幅度越小。月表电场的存在,会给电子反射法测量磁异常带来影响。随着电场强度的增加,月表磁场测量的分辨率会下降。因此,适宜选择在电场强度较低处开展电子反射法测量。通过对电场条件下的反射情况进行处理,从而得到电场的强度和磁场的实际分布,在一定精度下区分出相邻的不同月表磁场的差别;同时可以得到月面电场的分布。本文的工作将为今后的月球磁异常探测提供载荷配置、探测数据分析应用等方面的有用信息。
[Abstract]:Lunar exploration is one of the hotspots in deep space exploration at present, and the lunar surface magnetic field detection is the basic and key content. This paper first introduces the lunar surface magnetic anomaly and the lunar surface electric field, and discusses the significance and present situation of the lunar surface magnetic anomaly detection. The principle and method of detecting lunar surface magnetic anomaly by reflected solar wind electrons are also introduced. On this basis, the numerical simulation results of detecting lunar surface magnetic anomaly by electron reflection method are emphatically introduced in this paper. In this paper, the single particle orbital method is used to find the method and accuracy of distinguishing the different magnetic fields of the lunar surface by simulating the electron reflectivity and reflection distribution under different magnetic fields. The electric field of the lunar surface is also discussed in this paper. Through numerical simulation, the variation of electron reflectivity and reflection distribution under different electromagnetic field conditions are studied and analyzed, and the reasons for these changes are discussed in combination with theoretical formulas. It is proved that the electric field of lunar meter can be pushed back by the method of electron reflection and the influence of electric field on the method of electron reflection can be eliminated by formula. The main conclusion of this paper is that the reflection of solar wind electrons on the lunar surface changes with the change of the electromagnetic field conditions of the lunar surface. Moreover, the changes in the trajectory of the solar wind electrons caused by the changes of the magnetic field and the electric field can be distinguished: it is possible to qualitatively infer whether there are magnetic anomalies on the lunar surface through the reflection distribution. The magnetic field intensity of the monthly table can be further quantitatively calculated by combining the electron reflectivity with the magnetic field intensity at the satellite. The magnetic field is affected only by the ratio of the magnetic field intensity at the satellite orbit to the magnetic field intensity at the abnormal magnetic field, and the influence area of the electric field is omnidirectional. There are complex relationships between the charging condition of the monthly table and the illumination, the properties of the monthly surface, the plasma environment, etc. It is usually positively charged on the positive side of the monthly table, while in the shadow area, the monthly table is usually negatively charged. And there will be a potential difference between the moon surface and the satellite. This potential difference will have a profound effect on the work of measuring the monthly surface magnetic anomaly by the electron reflection method. In this paper, it is found by simulation analysis that for the same energy electron, the lunar surface band is positively charged. The greater the electric field intensity, the greater the critical angle of reflection and the less reflected; the greater the electric field intensity of the lunar band, the smaller the critical angle of reflection and the more reflection; for electrons with different energies, under the same electric field conditions, The higher the energy, the smaller the change of critical angle. The presence of the monthly surface electric field will affect the measurement of magnetic anomalies by the electron reflection method. With the increase of the electric field intensity, the resolution of the monthly surface magnetic field measurement will decrease. The electric field intensity and the actual distribution of magnetic field can be obtained by dealing with the reflection under the condition of electric field. At the same time, the distribution of the electric field of the lunar surface can be obtained by distinguishing the magnetic field of the adjacent moon surface with certain precision. The work in this paper will provide useful information for the future lunar magnetic anomaly exploration in terms of load configuration, data analysis and application.
【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】：博士
【学位授予年份】：2011
【分类号】：P184.5

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