The dynamics of particles in the magnetosphere during a substorm has been studied. The electromagnetic field of the magnetotail is assumed to be a dawn-dusk electric field and a two-dimensional neutral sheet magnetic ...The dynamics of particles in the magnetosphere during a substorm has been studied. The electromagnetic field of the magnetotail is assumed to be a dawn-dusk electric field and a two-dimensional neutral sheet magnetic field with Bz, where Bz varies with the distance from the earth. The numerical trajectories of the particles show that there is a non-adiabatic region near the equatorial plane, which is determined by δ = |(ρ·(?))B| /B>0.1 (ρ is the Larmor radius). The vanishing of the invariant μ leads to a pitch angle scattering. After a long time of scattering, most of the pitch angles of the particles become small enough for the particles to precipitate into the ionosphere. With the Tsyganenko model, the magnetosphere might be divided into 6 regions: the closed adiabatic region, the open adiabatic region, the non-adiabatic region near the equatorial plane of the near magnetotail, the non-adiabatic region in the cusp, the neutral sheet adiabatic region and the precipitation region. The precipitation region links the non-adiabatic regions with the aurora oval, which shows that the non-adiabatic region is one of the main sources of partide precipitation during substorms.展开更多
A three-dimensional （3-D） phantom for the density distribution of the plasmasphere is established. The imaging processes of the extreme ultraviolet （EUV） Imager are computer-simulated, in which the Earth shelter i...A three-dimensional （3-D） phantom for the density distribution of the plasmasphere is established. The imaging processes of the extreme ultraviolet （EUV） Imager are computer-simulated, in which the Earth shelter is treated as a main problem. A modified ART method is devised to resolve the incomplete data reconstruction problem to validate and evaluate the proposed methods. The cone-beam EUV data are simu- lated based on the 3-D phantom from both a circular and semi-circular trajectories. Quantitative reconstruc- tion results demonstrate the correctness of the proposed modified ART algorithm. The CT technique can be used to calculate the global density of the plasmasphere from the EUV data.展开更多
Field-aligned currents in the inner magnetosphere arc studied by using ISEE-2 magnetometer da-la, A method is proposed to calculate ×B with single-satellite data. From the morphology of ×B in time (or L). a ...Field-aligned currents in the inner magnetosphere arc studied by using ISEE-2 magnetometer da-la, A method is proposed to calculate ×B with single-satellite data. From the morphology of ×B in time (or L). a lot of large fluctuations are found in ×B near L = 5.5RE corresponding to the field-aligned currents. Statistical study shows that the field-aligned current in the inner magnetosphere is a function of B, L, MLT and AL. The region of the projections of ×B along the magnetic field line onto the ionosphere is not symmetrical for the geomagnetic pole. The inner boundary is independent of the geomagnetic disturbance, but during substorms the outer boundary shifts equatorward. The spatial distribution of the in- and out-flowing currents is complicated. The region-1-and-2 system is hardly distinguishable.展开更多
基金Project supported by the National Natural Science Foundation of China and the Chinese Academy of Sciences.
文摘The dynamics of particles in the magnetosphere during a substorm has been studied. The electromagnetic field of the magnetotail is assumed to be a dawn-dusk electric field and a two-dimensional neutral sheet magnetic field with Bz, where Bz varies with the distance from the earth. The numerical trajectories of the particles show that there is a non-adiabatic region near the equatorial plane, which is determined by δ = |(ρ·(?))B| /B>0.1 (ρ is the Larmor radius). The vanishing of the invariant μ leads to a pitch angle scattering. After a long time of scattering, most of the pitch angles of the particles become small enough for the particles to precipitate into the ionosphere. With the Tsyganenko model, the magnetosphere might be divided into 6 regions: the closed adiabatic region, the open adiabatic region, the non-adiabatic region near the equatorial plane of the near magnetotail, the non-adiabatic region in the cusp, the neutral sheet adiabatic region and the precipitation region. The precipitation region links the non-adiabatic regions with the aurora oval, which shows that the non-adiabatic region is one of the main sources of partide precipitation during substorms.
基金Supported by the National Natural Science Foundation of China (Nos.10575059,60871084,and 10905030)
文摘A three-dimensional （3-D） phantom for the density distribution of the plasmasphere is established. The imaging processes of the extreme ultraviolet （EUV） Imager are computer-simulated, in which the Earth shelter is treated as a main problem. A modified ART method is devised to resolve the incomplete data reconstruction problem to validate and evaluate the proposed methods. The cone-beam EUV data are simu- lated based on the 3-D phantom from both a circular and semi-circular trajectories. Quantitative reconstruc- tion results demonstrate the correctness of the proposed modified ART algorithm. The CT technique can be used to calculate the global density of the plasmasphere from the EUV data.
基金a grant from the National Natural Science Foundation of Chinathe Chinese Academy of Sciences
文摘Field-aligned currents in the inner magnetosphere arc studied by using ISEE-2 magnetometer da-la, A method is proposed to calculate ×B with single-satellite data. From the morphology of ×B in time (or L). a lot of large fluctuations are found in ×B near L = 5.5RE corresponding to the field-aligned currents. Statistical study shows that the field-aligned current in the inner magnetosphere is a function of B, L, MLT and AL. The region of the projections of ×B along the magnetic field line onto the ionosphere is not symmetrical for the geomagnetic pole. The inner boundary is independent of the geomagnetic disturbance, but during substorms the outer boundary shifts equatorward. The spatial distribution of the in- and out-flowing currents is complicated. The region-1-and-2 system is hardly distinguishable.
