Evolution Of Inner Magnetospheric Particles And Waves During Substorms

Substorms are an important driver of the evolution of particles and waves in the in-ner magnetosphere.Substorm-injected hot particles can destabilize plasma waves and then cause dynamics of the ring current and the radiation belt in the inner magneto-sphere.This thesis concentrates on the instrument design and data analysis regarding the substorm effect.In the first chapter,we introduce the plasma structures of the inner magnetosphere and their evolution characteristics during storm and substorms,and propose the research topics of this thesis.In the second chapter,we perform a preliminary design of the low energy ion spec-trometer.In view of the national demand for the low-energy ion detection on the 3-axis stabilized satellites in the medium and high Earth orbit,we carried out the size design and simulation of the top-hat type electrostatic analyzer of the space-based low-energy ion spectrometer by referring to the RBSP satellite and several main low-energy particle detection methods.The simulation results show that the design scheme can realize the half-space detection of low-energy ions,and the instrument parameters such as energy resolution,pole-angle resolution and geometric factor can meet the actual requirements of working in space.In the third chapter,we study the unexpected evolution of magnetosonic waves during substorms.The substorm injection of protons has long been expected to pro-duce proton ring distribution and excite magnetosonic waves through the ion Bernstein mode instability in the magnetosphere.Here we report the unexpected observations by the RBSP mission of the magnetosonic wave quenching associated with the sub-storm proton injections under both high-and low-density conditions.The enhanced proton thermal pressure distorted the background magnetic field configuration and the cold plasma density distribution.The reduced phase velocities locally allowed the weak growth or even damping of magnetosonic waves.Meanwhile,the irregularly spatial dis-tribution of refractive indices might suppress the cumulative growth of magnetosonic waves.For intense injections,this wave quenching region could extend over 2 hr in magnetic local time and 0.5 Earth radii in radial distance.These results provide a re-fined view of the evolution of magnetosonic waves during substorms.In the fourth chapter,we study the radiation belt electron acceleration driven by substorms.How the radiation belt electrons are accelerated to multi-megaelectronvolt energies has long been a fundamental question.Because the geomagnetic storms usually cause dramatic dynamics of the radiation belt electrons,most of previous studies focus on the electron acceleration during storms.However,because of the simultaneous ac-tions of multiple acceleration mechanisms,their respective contributions are difficult to be determined.Here we investigate the electron acceleration driven by substorms on the basis of the RBSP observations.Under the condition of southward interplanetary mag-netic fields,the successive substorms injected hot electrons to the inner magnetosphere,destabilized whistler-mode chorus waves outside the plasmasphere and eventually ac-celerated locally the radiation belt electrons at large L-shells.The resulted electron phase space density had a steep gradient along the radial direction,favoring the sub-sequent radial acceleration of electrons.These results provide a complete end-to-end picture of interplanetary disturbances causing geomagnetic activities and transferring energies to the radiation belt electrons through wave-particle interactions.In the fifth chapter,we summarize obtained results and propose future work.