Research On Generation Of ELF/VLF Waves Via Modulation Of Polar Ionosphere

It is of great scientific significance to modulate the ELF/VLF wave by the high-frequency carrier heating ionosphere.According to the research status and existing problems,it can be seen that the heating model coupled with the physical model is used for heating effect and modulation excitation ELF/VLF wave analysis has important scientific significance.Based on the ohmic heating theory,a heating model for the coupled low ionosphere physical model is constructed.Then,based on this,the heating effect and modulation excitation ELF/VLF wave theoretical simulation analysis are carried out.Finally,the comparative analysis and verification were carried out through the experimental data.The main work carried out is as follows:1 Starting from the continuity equation,considering the ionization sources such as photochemistry and mantle,high-energy electron deposition in the polar region,based on the constructed steady-state ion chemical framework,23 positive ions,11 negative ions,electrons and 12 neutrals are combined.The composition,involving 145 ion chemical reactions,finally established a polar zone low ionospheric steady-state physical model.Compared with IRI-2016,the physical model can better describe the morphological characteristics of the low ionosphere electron density in the polar region with height,diurnal variation and latitude variation.2 Based on the low ionospheric physical model of the polar region,a coupled heating model was established based on the ohmic heating theory.The heating effect simulation was compared and analyzed by using different incident modes(O wave and X wave).The results show that the coupled heating model is effective.3 The experimental data obtained by the amplitude modulation O-wave and X-wave comparison conducted by EISCAT on November 15,2017 were analyzed,and the numerical simulation of the ELF/VLF wave modulation excitation based on the coupled heating model was verified.The results show that X-wave heating excitation intensity is better than O wave,and the ground magnetic field amplitude of the excited low frequency wave at the receiving point of Breivikeidet ~15km away from Tromso site reaches ~0.1pT,which is basically consistent with theoretical simulation.