Research On The Configuration Of Magnetotail Lobe During Substorm Process

This master's thesis is divided into four parts, the first part is the introduction of the basic structure of the magnetic field and the background knowledge related to substorm. The second part is themagnetotail lobe magnetic field structure changes during substorms.The third part is the research of some typical substorms.The fourth part is summary.Substorm is always the most important problem in space physics. Substorm is consist of energy storage, release and dissipation process.The occurrence and development of the sub storm events involved in the whole process of the system, including the solar wind and interplanetary magnetic field, the magnetic layer and the ionosphere, the coupling of the upper atmosphere and so on.Intense substorm activities will cause a disturbance of the earth's space environment, including: particle events(substorm particle injection event, ionospheric particles event injection, radiation belt particle changes, ring current particles changes) in the magnetosphere, ionospheric storm, ionospheric disturbances and thermal structure change. These activities have an important influence on the operation environment of the satellite and the living environment of human beings.Tradition research to the magnetic field structure rely on a single satellite, can not be a good reflection of the three-dimensional structure of the magnetic field. We use multi point detecting method, can study the gradient magnetic field, magnetic curvature radius, magnetic rotation vector and the three-dimensional structure can be a good reflection of the magnetic field.The method provides a better way for us to study substorm..We selected some typical feature's substorm events for analysis.In the saw-substorm, we found that the variation of radius of curvature lines is very complex.In the event of external trigger's substorm event, we can see the existence of the field current and the non-field current.Finally, in order to make a more detailed study about substorm, we compared thesubstorm events with the quiet period in the same position. We comparative analysis of the magnetic field structure during substorm period and quiet period in the same location. In this paper, by using cluster four-point magnetic field measurements,we calculated the magnetic field gradient, and then we get the radius of curvature and binomial and so on.In the growth phase,because of magnetic field line stretch,radius of curvature increased. In the expansion phase, because of magnetic depolarization, radius of curvature reduced.In the recovery phase, radius of curvature return to the original value and represents a whole substorm activity. In the quiet period of the magnetic field, the gradient of the magnetic field is relatively small, only about 0 ~ 5 nT/RE.In the substorm period, the gradient of the magnetic field can be more than 10 nT/RE. And the value of the magnetic field gradient decreases slowly. In the substorm period and quiet period, there were no electric current observed. The change of radius of curvature is consistent with the magnetic configuration.So we can use the characteristic of magnetic field to reflect the substorm.