2012 Volume 7 Pages 1403156
Effects of a static magnetic island generated by an external magnetic field on the linear stability and the nonlinear dynamics of resistive interchange modes are numerically studied by means of the reduced magnetohydrodynamic (MHD) equations in a straight heliotron configuration. Equilibria consistent with the static magnetic island are examined, where the pressure profile is locally flat inside the separatrix. The linear growth rate of the interchange mode is decreased with the increase of the static island width. The mode is completely stabilized when the static island width exceeds a threshold value. The threshold width is almost the same as the half-width of the eigenfunction of the stream function obtained for the equilibrium without the static island. The saturation level of the kinetic energy in the nonlinear evolution is also decreased with the increase of the static island width.The island width and the pressure profile are also affected by the nonlinear saturation of the interchange mode.