tit
커뮤니티_visual 커뮤니티_visual

News

Train elite scientist with creativity and global leadership.

News

물리학과/첨단원자력공학부 특별세미나 개최 안내
물리학과2018-09-11444
페이스북으로 보내기 트위터로 보내기 구글플러스로 보내기

1. 연사: 유종수 박사 (Princeton Plasma Physics Laboratory)
2. 일시: 2018. 9. 17(월), 오후 2시
3. 장소: 공학3동 201호 (세미나실)
4. 제목: Energy conversion processes and wave generation during magnetic reconnection

 

In the Magnetic Reconnection Experiment (MRX), detailed laboratory studies of magnetic reconnection have been carried out over the last two decades. For the first part of this talk, the basic concept of magnetic reconnection is introduced and recent results from MRX related to energy conversion processes are presented. In ion heating and acceleration, the in-plane electrostatic field plays a key role [1]. On the other hand, the mechanism for the observed non-classical electron heating has yet to be identified [2]. The quantitative analysis of the energy inventory reveals that ions gain about twice more energy than electrons during antiparallel, symmetric reconnection [3]. Finally, effects of density asymmetry across the current sheet on magnetic reconnection and energy conversion are discussed [4, 5].

 

Various waves and instabilities can be generated during reconnection and make a significant impact on the reconnection dynamics. Here, whistler and lower-hybrid waves during reconnection are studied with data from the Magnetospheric Multiscale (MMS) mission and MRX. In particular, the dispersion relation of the whistler mode near the magnetospheric (low-density) separatrix is measured for the first time [6]. The measured dispersion relation shows that the whistler wave propagates nearly parallel to the magnetic field, which is consistent with a linear analysis. The linear analysis also confirms that the whistler wave is generated by temperature anisotropy in the electron tail population. Finally, we have observed in both laboratory and space plasmas that the lower-hybrid drift wave (LHDW) is excited inside the current sheet during reconnection with a sizable guide field. Initial results indicate that LHDW contributes to anomalous resistivity and electron heating in the current sheet.

 

[1] J. Yoo, M. Yamada, H. Ji, and C. Myers, Phys. Rev. Lett. 110, 215007 (2013).
[2] J. Yoo, M. Yamada, H. Ji, J. Jara-Almonte, and C. E. Myers, Phys. Plasmas 21, 055706 (2014).
[3] M. Yamada, J. Yoo, J. Jara-Almonte, H. Ji. R. M. Kulsrud, and C. E. Myers, Nature Comm. 5, 4774 (2014).
[4] J. Yoo, M. Yamada, H. Ji, C. E. Myers, J. Jara-Almonte, and L.-J. Chen, Phys. Rev. Lett. 113, 095002 (2014).
[5] J. Yoo et al. J. Geophys. Res. 122, 9264 (2017).
[6] J. Yoo et al. Geophys. Res. Lett. 45, 079278 (2018).