DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2013 EXPERIMENTAL CAMPAIGN Review | Direct submission with log-in | Request submission without log-in
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Title	79: 3D magnetics equilibrium measurements to applied n=3 perturbations
Name:	Josh King kingjd@fusion.gat.com	Affiliation:	Department of Energy
Research Area:	Stability & Disruption Avoidance	Presentation time:	Requested
Co-Author(s):	E.J. Strait and M.J. Lanctot	ITPA Joint Experiment :	No
Description:	Make first 3D magnetics measurements of the poloidal spectral changes on the inner wall due to an applied n=3 external I-coil perturbation. Specifically variations resulting from changes in q-profile, I-coil parity and βN are to be explored. This will provide a first test of the 3D magnetics sensitivity, and allow for detailed quantitative model validation (MARS-F, ect.) of the full eigenstructures resulting from applied n=3 perturbations.	ITER IO Urgent Research Task :	Yes
Experimental Approach/Plan:	The initial focus of this experiment is obtaining sufficient 3D signal for a physically relevant measurement, and will be followed by parameter scans. A lower single null ELMing H-mode discharge with the highest possible βN/li will be used. The plasma shape will be chosen to maximize kink mode coupling (upper triangularity ~ 0.1). The I-coils need to run at full current and polarity flips will be used to allow synchronous detection. Odd Parity: (1) Run at q95 ~ 5.0. (2) At fixed q95 ~ 5.0, scan βN as low as possible before 3D signal is lost. (3) At fixed βN/li, scan q95 as low as possible before disruptions and/or 3D signals are no longer observable. Even Parity: (4) Switch to even parity and repeat (1) through (3) Using the new 3D magnetics pair of vertical inner wall arrays, measure the poloidal spectrum. These spectra can be combined with the LFS measurements to obtain a full 3D reconstruction at the vessel wall. Note, for reconstructions at the wall to be related to the full 3D equilibrium at the surface of the plasma the shape will need to be fixed while q95 is scanned.
Background:	It has been predicted using MARS-F and IPEC models that fine 3D eigenstructures are apparent along the inner wall during external n=3 I-coil perturbations. Measuring changes in these inner wall poloidal spectra may elucidate a variety of physics topics associated with applied 3D fields (e.g. RMP and NTV). Testing this capability is the purpose of this experiment.
Resource Requirements:
Diagnostic Requirements:	The complete installation, testing and calibration of the 3D magnetics upgrade is required.
Analysis Requirements:	Existing magnetics plasma response analysis tools are needed. 3D reconstruction tools, used for 3D magnetics design work, will need to be further developed to use new sensor data and synchronous detection. Also, predictive modeling with MARS-F & IPEC will be used.
Other Requirements: