Linear simulation of kinetic Peeling-Ballooning mode with bootstrap current under the BOUT++ gyro landau fluid code

Abstract

The kinetic peeling-ballooning mode (KPBM) plays a crucial role in the edge turbulence and transport in a tokamak plasma. However, the impact of the bootstrap current on KPBM is still unclear. Simulations of KPBM using the BOUT++ gyro-Landau-fluid code are presented in this study. To investigate the KPBM in a real tokamak equilibrium, the global equilibrium solver CORSICA was employed to generate a set of realistic equilibria of shifted circular geometry, including the Shafranov shift, elongation effects and bootstrap current. The linear instability property of the KPBM is observed in a wide range of pressure gradient and parallel current density in the pedestal region. Our results indicate that the bootstrap current has a stabilizing effect on the high-n KPBM over the entire pedestal region. Here, n is the toroidal mode number. In comparison with the ideal magnetohydrodynamic peeling-ballooning mode stability diagram, the unstable KPBM region shrinks and shifts to low ( where denotes the pressure at the peak pressure gradient position) with the increase of the bootstrap current. Moreover, we find that the low-n kink modes are driven unstable by the bootstrap current in the second stable region. With an additional external current drive on top of the bootstrap current, the low-n KPBMs can be stabilized when the total edge current is sufficiently large, although the low-n kink mode is still unstable in the region with .