Magnetic-island-induced ion temperature gradient mode

摘要

Characteristics of ion temperature gradient (ITG) instability in the presence of a magnetic island are investigated numerically using a gyrofluid model. It is shown that when the magnetic island is wide enough to produce a broad distribution of rational surfaces near the 0-point region, the ITG perturbations at these rational surfaces form a radially global-type eigenmode with a fast growth rate, which is referred to as the magnetic-island-induced ITG (MITG) mode. Moreover, the magnetic island also causes both radial and poloidal mode couplings, which play a stabilizing role. This work was partially supported by the JSPS-CAS Core-University program in the field of 'Plasma and Nuclear Fusion'.