Validation of linear resistive plasma RMP response model with internal measurements on DIII-D

Plasma response plays an important role in understanding ELM control by resonant magnetic perturbations (RMPs). The MARS-F linear resistive plasma response model has been validated against the plasma internal measurement data from DIII-D ELM control experiments. Considered are DIII-D discharges where the n=1-3 RMP field was applied. Experimental data for the plasma boundary displacement, as well as the electron pressure perturbation in the edge pedestal region, are deduced based on a vertical Thomson scattering (TS) system and a horizontal charge exchange recombination (CER) system. The linear response model produces results that are in reasonably good quantitative agreement with the DIII-D internal measurements. Inclusion of the toroidal sideband contribution in the modeling is found to be important to properly recover the measured coil phasing dependence of the plasma boundary displacement. As an important insight, the larger plasma displacement measured by the vertical TS system, as compared to that by the horizontal CER system, is due to the contribution from the tangential component of the plasma displacement to the former. This study provides further confidence in the linear resistive plasma response model for analyzing ELM control experiments.