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	309: Full 3D Rotation optimization of H mode
Name:	Richard Buttery buttery@fusion.gat.com	Affiliation:	General Atomics
Research Area:	Stability & Disruption Avoidance	Presentation time:	Not requested
Co-Author(s):	All the people I speak to in stability	ITPA Joint Experiment :	Yes
Description:	The crucial limiting effect of error fields in H-modes comes through braking, which either opens the door to inherent tearing instability, or arrests rotation to drive locked modes directly. this most likely acts through NTV, with different 3D field sources of NTV possibly adding independently. Thus an approach to optimize the error field by rotation optimization, exploring the optimization in different I coils (or I-coil combinations) independently. A combined optimal EFC would result from combining these individual responses. Slow rotation feedback would be a good way to achieve each optimization	ITER IO Urgent Research Task :	Yes
Experimental Approach/Plan:	At medium betan, ramp current in an I coil to optimize rotation. If no discernible optimization raise betan. Introduce a slow feedback approach to rotation optimization to optimize current in coil. Repeat shot to shot with different coils. Once all coils done, then combine correction of individual coils, scaling current across all coils up and down together for the rotation optimization. (These are the principles, some compromises may be needed in implementation give available PSs and PS limits; might use some combinations of audio amps to add degrees of freedom - otherwise a lot of patch changes). (The rotation feedback optimization might be further improved using Frasinetti's proposed dithering technique)
Background:	TBM studies show that H mode, traditional error field correction only captures 25% recovery.
Resource Requirements:	Magnetic feedback control development. All possible RMP power supplies, augmented by suitable combination of audio amps. I coils.
Diagnostic Requirements:	Rotation - CER in real time
Analysis Requirements:	Some effort to implement rotation feedback linkage into 3D coils, and develop algorithm.
Other Requirements:	Someone to run this XP