Multi-Modal analysis of Linear MHD response to resonant magnetic perturbations in DIII-D plasmas

The impact of plasma triangularity on the plasma response to 3D magnetic perturbations for DIII-D plasmas is investigated to gain insight into its role in the suppression of edge localized modes. Evidence suggests the dynamics behind ELM suppression can be significantly altered by the 2D plasma shaping, namely the triangularity, to the point where ELM suppression may not be achieved with applied 3D fields [1]. Kinetic equilibria with self-consistently varied triangularity, pedestal density, and plasma beta obtained using the SEGWAY framework are processed using GPEC to calculate the liner 3D plasma response. We apply singular value decomposition to isolate how variations in plasma shaping alter the dominant harmonic content of the 3D response. A multi-modal focused W analysis across the parameter space is used to identify primary factors influencing the response. Specifically, we identify the two dominant mode structures by applying SVD to a phasing matrix built from the ideal displacement and magnetic perturbation vector fields. We then describe these structures using the individual W terms to assess how the modes' relative phase correlates with suppression access. This knowledge plays a pivotal role in optimizing plasma configurations and refining control strategies aimed at ELM suppression/mitigation. [1] Paz-Soldan C. et al, Nucl. Fusion 59 056012 (2019). Work supported by US DOE under grants DE-FG02-86ER53218, DE-FC02-04ER54698, DE-FG02-95ER54309, and DE-SC0022270.