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Title	144: Validation of kink response models with rotating n = 1 and n = 2 and phase flip n = 3 RMPs
Name:	Richard Moyer moyer@fusion.gat.com	Affiliation:	University of California, San Diego
Research Area:	ELM Control	Presentation time:	Requested
Co-Author(s):	D.M. Orlov, B. Tobias, L. Zeng, E. Unterberg, M. Shafer, A. Wingen, A. Turnbull	ITPA Joint Experiment :	No
Description:	Emerging understanding of plasma response to RMPs indicates that the response includes both rotational screening and kink response. The former reduces some resonant harmonics in the vacuum field by factors of 1.5â??3.5, much less than predictions from slab 2-fluid models, while the second amplifies the corresponding harmonics in the vacuum field. DIII-D has demonstrated the ability to measure the displacments of the boundary due to the kink response at the crown (top) using Thomson scattering, outboard midplane (fast camera, ECEI, profile reflectometry), and X-point (EUV/SXR imager). We have in addition new magnetics to measure the plasma response at the wall. Dedicated run time is needed to use these new diagnostics (new since CY11) to validate models of plasma response to RMPs using rotating n = 1 and n = 2 RMPs, and phase-flip n = 3 RMPs. Understanding the plasma response to magnetic perturbations is critical for understanding how these magnetic field affect ELM behavior, and will lead to a predictive model for ELM suppression in ITER. Multiple models are now available, including the vacuum TRIP3D-MAFOT model, and the MARS-F, M3D-C1, and XGC0 models. In addition, these perturbative models generate a very different kink response on the HFS along the centerpost from the global VMEC model.	ITER IO Urgent Research Task :	No
Experimental Approach/Plan:	Establish "conventional" low collisionality ELMing H-mode. Apply rotating n =1 and n = 2 RMPs at 10 Hz, and phase flip n = 3 RMPs. Use existing diagnostics to resolve the boundary displacements versus poloidal angle, and to document transport changes and the external kink n is varied. Scan collisionality, RMP amplitude (I-coil current), non-resonant vs. resonant componets (parity) and phasing with respect to intrinsic error fields to document the variation in kink response. Reverse Bt to change the direction of the poloidal rotation of the displacement (change helicity of field-aligned structure). Vary q95 which impacts the magnitude of the displacement. Vary target plasma rotation which should vary the balance between rotational screening and kink amplification.
Background:	Understanding the plasma response to externally applied magnetic perturbations is critical for understanding how these magnetic fields effect ELM behavior, and will contribute to a predictive model for ELM suppression in ITER. The DIII-D program has demonstrated an extensive diagnostic set (high resolution Thomson scattering, fast BES imaging spectroscopy, EUV/SXR imaging, ECEI, profile reflectometry, fast CER, and improved magnetics) to measure the plasma response versus poloidal angle which allows us to separate the rotational screening, kink amplification, and vacuum manifold displacements. Despite substantial efforts in CY11 and CY12 to develop these diagnostic measurements, very little run time has been allocated to advance the preliminary measurements to their fullest capability of testing the plasma response models. This experiment will capitalize on these diagnostic investments.
Resource Requirements:	I-coil with n = 1, n = 2 and n = 3 rotation and phase flips Bt = - 2T to provide ECE and ECEI data missing from CY11 data 150R beam unmodulated for BES imaging 210 beams to vary torque input and rotation Full pedestal and profile diagnostics UCSD 90R0 passive imaging of high field side UCSD 225R0 active BES of 150R
Diagnostic Requirements:	Primary diagnostics are the UCSD fast camera, requiring 150R unmodulated, and ECE measurements (ECE and ECEI), requiring increased toroidal field to at least 2 T. Full turbulence diagnostics to monitor fluctuation response as the relative strength of kink versus rotational screening is varied to identify origin of the turbulence changes.
Analysis Requirements:	Profile and kinetic equillibrium analysis. Plasma response modeling of selecting "best" cases: MARS-F, M3D-C1, VMEC, etc. TRIP3D-MAFOT determination of the manifold displacements for the vacuum and plasma response models.
Other Requirements:	--