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작성일 : 17-06-09 09:37
06월 15일(목요일) 우주과학과 세미나 안내(서정준박사님)
 글쓴이 : 관리자
조회 : 153  
안녕하세요우주과학과 여러분.
 
이번 세미나는 6 15일 오후 1 30천문대 영상실에서 있습니다.
한국천문연구원의 서정준 박사님께서 "Plasma kinetic instability and its application to the solar wind electron"에 관한 강연을 해 주실 예정입니다. 강연은 한국어로 진행되며초록은 아래에 나타나있습니다.
 
세미나 참석을 원하시는 분은 세미나 시작 10분 전까지 입실해 주시기 바랍니다.
 
많은 참석 부탁드립니다감사합니다.
 
 
Dear Colleagues,
 
There will be an Astronomy and Space Science seminar on 06/15, 4:30 PM, in the Auditorium, Kyung Hee University Astronomical Observatory. Dr. Jungjoon Seo ugh of Korea Astronomy and Space Science Institute (KASI) will give a presentation about "Plasma kinetic instability and its application to the solar wind electron."
The language of the seminar will be Korean and abstract is shown below.
  
You are asked to join the seminar five to ten minutes before it starts. Your attendance will greatly be appreciated.
 
 
Thank you.
 
 
Abstract:

 The solar (stellar) wind plasma is known to originate in the upper atmosphere of the Sun (ordinary star) and expand through interplanetary space. Among multi- species particles, the electrons play important roles in driving the expansion of the solar corona and transporting the solar wind energy through the heat flux. The properties of solar wind such as low number density and high temperature imply that Coulomb collisional rates among particles remain very low for reaching thermal equilibrium. In a weakly collisional plasma, in situ measurements have shown that the velocity distribution function of solar wind electrons typically deviates from a Mawellian and exhibits non-thermal features such as temperature anisotropy, electron beams, and the differential flow of suprathermal halo electrons with respect to thermal core electrons. Such non-thermal features could be possible sources of free energy that can drive many different types of plasma kinetic instabilities, resulting from the gradient of the velocity space. The enhanced fluctuations driven by instabilities scatter particles in phase space and eventually drive the velocity distribution functions toward marginally stable state through wave-particle interactions. Recently, many observations have revealed that those instabilities could occur in the solar wind and contribute to the dynamical evolution of particles. It is the purpose of the present talk to disseminate the idea that plasma kinetic instabilities are important for understanding the origin of the observed electron velocity distribution functions and the electromagnetic fluctuations of the electron scales in the solar wind. Among various instabilities, we shall focus on the whistler and heat flux instabilities. By making use of both linear Vlasov theory and particle-in-cell simulation, we shall present the recent results associated with the solar wind electron dynamics.