Determination of solutions for chorus excitation mechanism characteristic equation by means of Van Allen probe data analysis

Abstract

In this paper, we focus on studying the quantitative characteristics of the excitation mechanism of chorus emissions closely related to the problem of relativistic electron flux formation in the radiation belts. The study is based on the processing of information accumulated by the Van Allen Probe spacecraft through the analysis of high-resolution data. We have chosen two typical examples of chorus emissions with spectral forms predominantly in the upper-frequency band (above half the electron cyclotron frequency) in the region of the local minimum of the magnetic field outside the plasmapause in the middle magnetosphere. We have developed and implemented a calculation algorithm that enables us to represent the results of wave field measurements in a high-resolution data channel in the form of a rectangular event matrix, each row of which corresponds to a cycle of the wave process. In the event matrix, we select the rows corresponding to fragments of chorus emissions that best characterize the natural source of short electromagnetic pulses. This method made it possible to determine the complex eigenvalues of the characteristic equation of the chorus emissions source. The proposed method for processing experimental information makes it possible to determine the main characteristics of the linear mechanism of chorus excitation. The results obtained in this way from observational data are in good agreement with relevant theory of chorus emissions excitation by amplifying noise electromagnetic pulses in a duct with a depleted density of a cold plasma.