* BK21/ PHYSICS 특별세미나 *

New Insights to the Classical m/n=1/1 mode ("Sawtooth Oscillation") in Hot Plasmas based on High Res

연사: 박현거[Princeton Plasma Physics Laboratory]

일시: 2007 년 5 월 18 일 13:30-15:00

장소: 공학3동 세미나실(201호)

ABSTRACT:

"Microwave Camera" with a high spatiotemporal resolution has been developed to study the physics of the classical m=1 mode ("sawtooth oscillation") in high temperature tokamak plasmas (TEXTOR, Germany). Review of the physics of the classical m=1 mode given by comparative studies with prominent theoretical models suggests that a new physics paradigm is needed to describe the reconnection physics of the m=1 mode. 2-D imaging data from the "Microwave Camera" provided key new physics which were not available in previous studies largely based on the 1-D electron cyclotron emission measurement and X-ray tomography. The new insights are: A pressure driven instability with n~3 and m>10 modes (not a pure ballooning mode)leads to the “X-point” rather than the "Y-point" reconnection process originated from the "Sweet-Parker" reconnection model. The reconnection time scale is still significantly faster than the resistive time scale for both kink and tearing type of the m=1 mode. The concept of well accepted global field line stochasticity which resolved the discrepancy between the instantaneous plasma pressure transport and almost invariant magnetic flux during the reconnection phase is challenged by demonstrating that the heat flux motion during reconnection time scale is highly collective. Finally the reconnection process during the crash is much more complex than previously addressed and identified as a random 3-D local reconnection process.

문의처: 정윤희(054-279-2078, yhj@postech.ac.kr)