Shaping effects on non-ideal ballooning mode

The dependence of shaping effects on the growth rate of collisionless and resistive ballooning mode (CBM/RBM) is numerically investigated. That of the drift ballooning modes (DCBM/DRBM) is also investigated by taking kinetic effects into account. Resistivity scans of linear growth rates of CBM/RBM and DCBM/DRBM in a circular geometry show that both modes have 3 branches in accordance with decreasing resistivity, fast, resistive and collisionless branch. The last two branches are in the edge relevant resistivity regime and are in the scope of this paper. For CBM/RBM, shaping effect on the growth rate becomes weak with increasing resistivity and the growth rate monotonically increases with decrease of the elongation and increase of the triangularity, on the other hand, the opposite tendency appears on the triangularity for DCBM, namely it weakly decreases with increase of the triangularity. This fact indicates that the inverted D-shaped equilibrium can be unstable against DCBM compared with the D-shaped equilibrium. © 2019 The Japan Society of Plasma.