Academic Lecture鈥斺€擮n the Generation of Banded Chorus

Time: 10锛?0 a.m Friday, July 7锛?023
Place:Lecture Hall, 5th Floor, School of Electronic Information, Wuhan University
Speaker:Kyungguk Min

Abstract:
Whistler-mode chorus waves in the magnetosphere have been known since the dawn of space age. Chorus is best known for its rising (and sometimes falling) tones. It is generally agreed that the generation of such frequency chirps involves nonlinear physics involving phase bunching and trapping in an inhomogeneous magnetic field. Another well-known feature of chorus is a gap in intensity near half the electron gyro-frequency, fce/2, in which case it is called banded chorus. Although there have been many models proposed to explain this intriguing phenomenon, the origin of the intensity gap is still under active investigation. One model that is of interest here suggests that waves at fce/2 are selectively damped (as a result of cyclotron resonance) owing to a particular structure of electron distribution function, called the parallel plateau (which is essentially a relatively isotropic population in an intermediate energy range). The main part of the presentation will go through the development of this mechanism and how a new nonlinear process involving the parallel plateau may provide additional damping in excess of nonlinear wave growth.

Biography:
Kyungguk Min earned his Ph.D. in Space Physics from New Jersey Institute of Technology in 2013. After two postdocs between 2013 and 2018, he moved to Chungnam National University in 2019 where he has since been serving as an assistant professor in the Department of Astronomy and Space Science. His main research interest is various plasma waves in the terrestrial magnetosphere and their role in the acceleration and depletion of radiation belt particles.