Stability of ideal and non-ideal edge localized infernal mode

摘要

Stability of a special class of the infernal mode, i.e., the one which is localized near the plasma edge, is numerically investigated for a toroidal plasma, using the single fluid code MARS-F [Liu et al., Phys. Plasmas 7, 3681 (2000)] and magneto-hydrodynamic-kinetic hybrid code MARS-K [Liu et al., Phys. Plasmas 15, 112503 (2008)]. Unlike the peeling-ballooning instabilities, which are thought to be responsible for the onset of type-I edge localized modes, the edge localized infernal mode may be responsible for accessing certain quiescent H-mode regimes in tokamak discharges. The finite plasma pressure near the plasma edge drives this instability. The local flattening of the safety factor near a rational surface at the plasma edge region, due to the large bootstrap current contribution in H-mode plasmas, is a necessary condition for the mode instability. It is found that the plasma toroidal flow shear in the pedestal region, as well as the plasma resistivity, further destabilizes the edge localized infernal mode. The drift kinetic effects from thermal particles, on the other hand, partially stabilize the mode. The flow shear and the drift kinetic effects also modify the symmetry of the mode spectrum, by enlarging the unstable domain towards higher local qmin value. No substantial modification of the mode eigen-structure is observed by the plasma flow, resistivity, or the kinetic effects. These results can be relevant to understanding physics of certain quiescent H-mode regimes. Published by AIP Publishing.