Importance of the electron plasma parameter for excitation of chorus and formation of magnetic field irregularity in the region of their excitation
Journal Title: Solar-Terrestrial Physics - Year 2024, Vol 10, Issue 3
Abstract
A threshold condition has been established for excitation of VLF electromagnetic radiation with a chorus structure of the dynamic spectrum in the daytime magnetosphere using the BPA (Beam Pulse Amplifier) mechanism for amplifying short noise electromagnetic pulses. The kappa distribution was used as a model function of the electron velocity distribution in the magnetosphere. Calculations performed for this distribution have shown that the threshold for excitation of chorus largely depends on the electron plasma parameter equal to the ratio of gas-kinetic pressure of electrons to magnetic pressure. This pattern is not contradicted by the dependence of the probability of excitation of chorus on the degree of magnetic field irregularity, which we derived from observations made by the Van Allen Probe spacecraft. It is sharp fluctuations in the magnetic field strength near its local minima outside the plasmasphere where the radiation under study can be excited. If there is an irregularity, the probability of detecting chorus is >70 %; and if there is no or very low irregularity, the probability of the absence of any emissions is ~80 %. The results indicate a common reason for the excitation of chorus and the magnetic field irregularity — a small but finite value of the plasma parameter.
Authors and Affiliations
Bespalov P. A. , Savina O. N. , Zharavina P. D.
Keywords
Related Articles
- EP ID EP753793
- DOI 10.12737/stp-103202410
- Views 28
- Downloads 0
CALIBRATION OF SIBERIAN RADIOHELIOGRAPH IMAGES
We discuss the method for automatic calibration of solar radio images derived from the first stage of the multiwave Siberian Radioheliograph (SRH-48). SRH is a 48-element T-shaped radiointerferometer in the 4–8 GHz frequ...
SIGNS OF ANOMALOUS BEHAVIOR OF THE IONOSPHERE IN 2003–2014 AT F1-LAYER HEIGHTS OVER IRKUTSK
We have detected an anomalous electron density Ne increase in winter months in Irkutsk in some years of the period 2003–2014. This effect was manifested when we compared the experimental values obtained by the Irkutsk io...
DIAGNOSTICS OF EMISSION INTENSITIES AND ELECTRON DENSITY IN AURORAS BASED ON EMPIRICAL PRECIPITATION MODELS
We have studied the influence of the precipitating electron spectrum shape on the integral intensity of emissions λ391.4 nm 1NG N⁺₂, λ670.4 mn 1PG N₂, λ337.1 nm 2PG N₂, λ320.0 nm VK N₂, λ127.3 nm LBH N₂, atomic oxygen em...
APPLYING THE METHOD OF MAXIMUM CONTRIBUTIONS TO THE MAGNETOGRAM INVERSION TECHNIQUE
Fundamentals of the spherical harmonic analysis (SHA) of the geomagnetic field were created by Gauss. They acquired the classical Chapman — Schmidt form in the first half of the XXth century. The SHA method was actively...
INFLUENCE OF THE VONGFONG 2014 HURRICANE ON THE IONOSPHERE AND GEOMAGNETIC FIELD AS DETECTED BY SWARM SATELLITES: 2. GEOMAGNETIC DISTURBANCES
Strong meteorological disturbances in the atmosphere, accompanied by the generation of waves and turbulence, can affect ionospheric plasma and geomagnetic field. To search for these effects, we have analyzed electromagne...