Study On Periodic Variation Characteristics Of High Energy Electrons In Near Earth Space By Wavelet Analysis

In recent years,spacecraft of various countries have been launched one after another.In the process of space exploration,the communication and operation of satellites are seriously affected due to the instability of space environment,especially the high-energy electrons of Me V energy in the outer radiation belt.As we all know,the complexity of radiation band dynamics and its important significance in space weather,and the main difficulty in understanding electron dynamics lies in the randomness and universality of radiation band response.Although space physicists have always regarded the radiation zone environment as an important research object,the physical characteristics and motion mechanism of this space high-energy particle are still unclear.Therefore,it is urgent for us to conduct in-depth analysis and improvement.Solar wind,interplanetary conditions,geomagnetic activity and radiation zone are closely related.Due to the adverse effects caused by the rapid change of high-energy electron flux,physicists always focused on the drastic change of high-energy electron flux in the past.For example,the modulation of solar wind conditions,the influence of large magnetic storms on electron flux,deep dielectric charge and discharge,the internal wave particle interaction mechanism,or the prediction of high-energy electron flux.Different from previous research work:（1）Firstly,the periodicity of high-energy electron flux ≥ 2 Me V of China’s Fengyun-2 series satellites and goes series satellites is systematically studied by using wavelet analysis method.It is found that the fluxes of the two types of satellites have the same short period: 9 d,13.9 d and 27.7 d;Different medium and long periods: goes satellite has187.0 d and 342.9 d,and Fengyun-2 satellite has 222.3 d and 374.0 d medium and long periods.（2）The short period similarity of different satellites is further explained and analyzed.Based on the previous research conclusions,the differences of medium and long periods are reasonably speculated.It is found that the response anisotropy of two types of satellite fluxes to geomagnetic disturbances.And different from previous studies,when there is no geomagnetic storm but the Dst（disturbance storm time）index decreases,it can have the same effect on the electron flux as when there is a geomagnetic storm.（3）In order to further study the acceleration and loss mechanism of high-energy electron flux,we selected goes satellite with relatively stable data to analyze the response of ≥ 2 Me V high-energy electron flux in the absence of geomagnetic storm（Dst >-30 n T）event.It is found that the decline of Dst index in the absence of geomagnetic storm is as effective as that in the presence of storm,but it is not easy to increase the flux,And enhancement events are more likely to occur when the Dst index decreases more and lower Dst min.In addition,the decrease of Dst index can also well separate the sharp change and constant state of high-energy electrons.With different solar wind parameters,high-energy electron flux will have completely different responses,such as early arrival of high solar wind density,solar wind dynamic pressure and substorm activity.（4）Through in-depth study of the relationship between all events and solar wind parameters and geomagnetic index,it is found that higher solar wind speed,substorm for a certain time rather than long-term persistent substorm,low solar wind density and solar wind dynamic pressure are the key factors of electron acceleration.For example,in the event of no flux change,despite the existence of long-term persistent substorm and low solar wind density,However,due to the fluctuating speed of the solar wind and the always high dynamic pressure of the solar wind,the electrons still do not accelerate.The results of this paper reveal the periodic variation characteristics of high-energy electron flux,and it is found that the flux change is actually the result of the interaction of various parameters.The different conclusions drawn by different satellites lead to many interesting and worthy of in-depth problems,which provide more references and possibilities for the study of electron dynamics in the radiation zone in the future.