Statistical Analysis Of Global Distribution Of Electrostatic Electron Cyclotron Harmonic Under Different Geomagnetic Conditions

The radiation belt is an important region for the Earth's magnetosphere to capture particles.It includes two parts:the inner radiation belt and the outer radiation belt.The inner radiation belt contains high-energy protons and the outer radiation belt contains high-energy electrons.During geomagnetic storms and substorms,high-energy particles in the radiation belt can cause serious damage to the space technology system and the health of astronauts.Current research shows that,Electrostatic electron cyclotron harmonic(ECH)waves can affect the magnetic local time(MLT)distribution of plasma sheet electrons in space.When ECH waves interact strongly with the electrons of-keV,it contributes to the precipitation of electrons in the diffuse auroral zone,ECH waves are excited via the instability of the electron loss cone,its distribution can produce an effective scattering loss of plasmas sheet electrons,which has a significant effect on the dynamics of the outer magnetosphere.Therefore,it is necessary to study the global distribution of ECH waves under different geomagnetic conditions.In this paper,the global distribution of ECH waves under different geomagnetic conditions was studied using the data of Van Allen detector from October 1,2012 to June 30,2017.We also calculate the peak-to-valley ratio(Rpv)of 1 to 10 keV electron PSD at the pitch angle ?=90° when the ECH wave occurs.We have discovered a total of 419 ECH wave events by screening the spectrum data of electromagnetic waves.The statistical results show that:The ECH wave can occur in the entire region of L=3-6,MLT=00-24,and happens more in the region of L=5-6,MLT=06-19.The number of ECH wave events decreases as the geomagnetic index AE and Dst increase,and increases as the number of magnetic shells L increases.The electron phase space density will have ring distribution when the ECH wave occurs,the value of Rpv is basically between 1 and 3,and the ratio of Rpv will increase with the increase of AE and Dst.Compared with the Dst index,the effect of the AE index on Rpv is more obvious.For the first time,we relate ECH wave to the electron ring distributions,and the results provide an important basis for the subsequent theoretical modeling.