| The tail plasma sheet is a primary reservoir for hot plasma in the magnetosphere. The hot plasma from the geomagnetic tail drift earthward and pass by around the Earth in the near Earth region, forming a trough with lack of hot plasma around the Earth. The interface between the plasma sheet and the trough is the inner boundary of the plasma sheet. This boundary is usually located about 10 RE in the tail region during quiet period, but can move earthward during geomagnetic active period, causing the hot plasma to penetrate into the inner magnetosphere, even into the plasmasphere. Plasma sheet particles injected into the inner magnetosphere have significant influence on the ring current enhancement and the dynamic of the outer radiation belt. The hot dense plasma can also cause space weather hazard effects such as spacecraft surface charging. So studying the condition and the mechanisms for the plasma sheet access to the inner magnetosphere is important to understanding the formation of the magnetic storm ring current and the evolution of the outer radiation belt, as well as the development of the space weather prediction. In this dissertation, we perform theoretical and observational studies on the penetration of the plasma sheet particles into the inner magnetosphere, summarized as follows:We first analyzed the mapping of the magnetic equator to the(U, B) plane in sophisticated electric and magnetic field models. The dawn and dusk separators are calculated numerically. Our results show that the magnetic equator cannot be simply divided into two parts by the dawn and dusk separators on each of which a point has one to one corresponding(U, B) coordinates. The tailside part overlaps on itself in two regions in the(U, B) plane. By adding two auxiliary lines, the magnetic equator can be divided into four parts, and mapped in three separate plots in the(U, B) plane. Tracing the drifting process of a particle can be very complicated in the three separate plots in the(U, B) plane, though the trajectories of particles are still straight lines in them. In this situation, to find a tangent line to the discrete numerical separators with given slope is difficult, and moreover, the tangent line to the separators dividing the open orbit region from the closed orbit region can not be demonstrated in the(U, B) plane any more. We theoretically deduced that the tangent point of the particle drift orbit to the separator curves in the(U, B) plan is the counterpart of the stagnation point of particle drift in the real space. Based on this conclusion we developed a new numerical technique to calculate the Alfvén layer. This method has advantage of being adequate to sophisticated electric and magnetic field models. We use this method in explaining the statistical results of electron flux data measured on geosynchronous orbit presented in previous work. We get results different from previous work and find that the combination of Volland-Stern(V-S) and dipole+T89 models can explain the observation better than simple analytic models.Taking advantage of our new technique for Alfvén layer calculating, we calculated the cutoff energy curves in ion energy spectrum using combination of dipole+T96 and V-S models and combination of dipole and V-S models. We compared the cutoff energy curves that calculated using dipole model and dipole+T96 model in selected observation events. The comparison shows that the two kind model calculation results are nearly identical in the energy range below ~10 keV. They have large discrepancies in the energy range above ~10 keV out of ~ 5 RE, the cutoff energies calculated using dipole model are smaller. We compared the model calculated cutoff energy curves with the observed ion energy spectrum, and found that choosing proper Kp values, the calculated cutoff energy curves can match the observation well in lower energy range(near ~1 keV). The proper Kp values are nearly the largest Kp in previous several hours, indicating that change of the inner edge of the ion plasma sheet with Kp index have delay time of at least several hours. The discrepancies between the model calculated results and the observation are on the tips of the “nose†and in the higher energy(above ~10 keV) range and associated with local time. In the higher energy range(above ~10 keV) the cutoff energy curve calculated with dipole+T96 model are more close to the observation than that calculated with dipole model.We performed a statistical analysis on the relationship of the inner edge of the electron plasma sheet(IEEPS) with Kp index and AE index, respectively, and a dynamic model of the IEEPS is established taking these two indices as input parameters. A list of satellite IEEPS crossing events has been collected form electron data measured by THEMIS A, D and E in three years from 2009 to 2011. The statistical analysis results show that in the local time sector 17-10 MLT, both Kp index and AE index can have good correlaiton with IEEPS when proper delay times are set in each local time bin. We take the delay time that maximize the absolute value of the correlation coefficient as a measured value of the delay time in each local time bin and using these measured delay time, two different functions of delay time varying with local time for Kp index and AE index are found. For Kp index, the delay time increase linearly with local time from dusk to morning. For AE index, the delay time stay at zero from dusk to midnight and then increases linearly with local time from midnight to morning. Though the local time delay time functions for Kp index and that for AE index are different, they show the same trend that the delay time increase eastward around the Earth. This result is consistent with the direction of the electron drifting around the Earth, and suggests that delay time may be caused by the drift-time-effect of the injected electron from the pre-midnight region of the plasma sheet. Since in most cases the large scale electric field associated with Kp index and the local pulse electric field associated with AE index influence the IEEPS simultaneously, the new model of the IEEPS is established combining characters of IEEPS varying with Kp index and AE index. It is a dynamic model based on the delay time functions for Kp index and AE index.We established an empirical model of the location of the inner edge of the ion plasma sheet(IEIPS) using hot ion data recorded by HIA of TC-1/DSP. To study the variation of the radial location of the IEIPS, we divided local times(LT) into eight local time bins and fit the linear model R = A + B·Kp to the data points of pairs of the radial location R of the IEIPS and the instantaneous Kp index in each local time bin. We got eight linear functions of the variation of the radial location of the IEIPS with the Kp index. During quiet times(Kp ≤ 1.67), the closest part of the IEIPS to the Earth is in the local time bin 1930-2230, and the farthest part of the IEIPS to the Earth is in the local time bin 0430-0730. The rate of change of R with Kp in local time bins 2230-0130 and 0130-0430 are the two largest(B =-0.66 and-0.67). this means that when Kp changes, these two parts of IEIPS move fastest. According our model, when Kp increases smoothly from zero, the IEIPS penetrate into the geosynchronous orbit firstly in local time bin 1930-2230, then extend gradually toward both side local time bins. |
