Stochastic boundary modeling by resonant magnetic perturbations on DIII-D

A 3-D field line integration code (TRIP3D) is used to trace stochastic field lines in the edge of DIII-D plasmas in which edge localized modes (ELMs) are suppressed by resonant magnetic perturbations (RMPs). In these experiments normalized RMPs of 2.6 × 10−4 on the 95% flux surface produce complete ELM suppression, while global confinement stays high. The particle and heat diffusion coefficients produced by stochastic magnetic field on 95% flux surface have been calculated without and with ELM suppression. They are different from experimental results. The reason is that stochastic quasi-linear diffusion theory cannot be applied for the experimental explanation due to the complex nature of the transport physics involved when boundary layer field lines connect regions of hot plasma directly to material surfaces.