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 9
- Downloads 0
ESTIMATED EQUIVALENT RADIATION DOSE AT DIFFERENT ALTITUDES IN EARTH’S ATMOSPHERE
The paper reports the results of simulation of cosmic ray proton transport through Earth’s atmosphere. The main objective of this work is to obtain characteristics of secondary particle fluxes at different altitudes and...
MEASUREMENT OF ENERGY DISTRIBUTION FOR LOW POWER NANOFLARES
We propose a method to measure the energy distribution of low-energy flares (nanoflares) in the energy range below 1023 erg. As an example, we measured the spectrum of nanoflares in the 1021–1026 erg range for two Sun’s...
CHARACTERISTICS OF DOUBLE SODIUM LAYER OVER HAIKOU, CHINA (20.0° N, 110.1° E)
We study the property of double sodium layer structures (DSLs) in the mesosphere and lower thermosphere (MLT) by a lidar at the low-latitude location of Haikou (20.0° N, 110.1° E), China. From April 2010 to December 2013...
ESTIMATING ANTENNA COUPLING FACTOR FOR PROBLEM OF TOPSIDE IONOSPHERE SOUNDING FROM SPACE BY CHIRP SIGNALS
When developing the first topside ionosphere sounding stations, the issue was debated concerning the improvement of the electromagnetic compatibility of such devices through the use of chirp signals. One of the main prob...
IONOSPHERIC RESPONSE TO THE PASSAGE OF TYPHOONS OBSERVED BY SUBIONOSPHERIC VLF RADIO SIGNALS
The response of the lower ionosphere to the passage of several dozen typhoons has been studied using a regional network of VLF stations in the Russian Far East. The experimental data presented in all cases clearly demons...