Plasma profile and magnetic topology self-organization with total-f gyrokinetic KBM turbulence*

Kinetic ballooning modes (KBMs) in the first stability regime may set the upper bound of plasma performance in a fusion reactor and needs to be understood at kinetic level.  The total-f electromagnetic gyrokinetic code XGC is used to study  for the first time how the plasma profile evolves to self-organize with the KBM saturation.  The self-organization involves magnetic reconnection and island formation around the mode rational surfaces, and neoclassical and zonal flows.  Unlike in a reduced delta-f simulation, the total-f growth rates of KBMs are abated to be much smaller than the linear growth rates due to rapid "giving-in" of the plasma slope around the mode rational surfaces.  The saturated radial transport fluxes are found to be not much greater than those from ITG/TEM turbulence.   Modification of the magnetic surface topology around the mode rational surfaces caused by KBMs could affect other important physics, such as the energetic particle instability and confinement.