2/1 mode is one of the most frequent magnetohydrodynamic instabilities in tokamaks. The rapid growing of 2/1 mode (e.g. Locked mode) frequently lead to disruptions and associated vertical displacements when operating near density limit. Recently, scientists in ASIPP have found that the rapid growth of m=2 island can convert to m=1 mode in very high density plasma, and only lead to series of internal disruptions, therefore successfully avoid the major disruption.
This m=2 island onset occurs when the ohmic heating input is less than the radiative cooling loss, which agrees with the mode onset behavior of the thermo-resistive model.
The relevant research result was published in the Nuclear Fusion journal (Liqing Xu et al. “Radiation-driven m = 2 island formation and dynamics near density limit in experimental advanced superconducting tokamak ohmic plasma” 2017 Nucl. Fusion 57 126002).
Repetitive burst of m=2 island in high density operation plasma
Article link: http://iopscience.iop.org/article/10.1088/1741-4326/aa7f91
This work was supported by the National Nature Science Foundation of China under grant nos. 11505226 and 11575247 and the JSPS-NRF-NSFCA3 Foresight Program in the field of Plasma Physics (NSFC) under grant no. 11261140328.
(Liqing XU reports)
