Self-Consistent Simulation of Kinetic Pedestal Transport under RMP Penetration

Full text: We report a significant new theoretical understanding of the ELM-stable edge pedestal behavior under resonant magnetic perturbations (RMPs). Coupled kinetic and extended MHD simulation in a realistic magnetic separatrix geometry, with electrons and ions orbiting under plasma screening of the externally applied RMPs, self-consistent radial electric field Er, Coulomb collisions, and neutral kinetic transport, is presented for the first time which shows that RMP amplitude is significantly shielded around the magnetic separatrix/pedestal region by plasma response, the magnetic field stochasticity survies deep into the plasma, and that ne is significantly reduced without the collapse of Te in a manner qualitatively consistent with experiments. The study reveals why the standard Rechester-Rosenbluth model is not applicable to the tokamak edge plasmas. For the kinetic edge transport simulation, we use the full-function kinetic ion-electron-neutral guiding-center PIC code XGC0. For the RMP penetration into the plasma across the scrape-off, we use the M3D extended MHD code. It is found that a significant local screening of the RMP amplitude occurs around the magnetic separatrix and pedestal, and that a significant level of stochasticity survives the plasma shielding in DIII-D deep into the main plasma. Analysis of the kinetic transport in XGC0 reveals that the kinetic trapped particle effect is essential in understanding the stochastic plasma transport in a toroidal magnetic confinement device. Detailed experimental validations will not be limited to the conventional tokamaks, such as DII-D and JET, but will be extended to the low-aspect devices, MAST and NSTX, which have much stronger trapped particle kinetic effects than DIII-D or JET does. Predictions for ITER plasma will also be attempted. (author)