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Title	187: H-mode 3-D field optimization with purely kink-resonant and non-resonant n=1 fields
Name:	Carlos Paz-Soldan paz-soldan@fusion.gat.com	Affiliation:	Columbia University
Research Area:	Stability & Disruption Avoidance	Presentation time:	Requested
Co-Author(s):	M.J. Lanctot, E.J. Strait, R.J. La Haye, J.M. Hanson, J. King, J-K. Park, N. Logan, N. Ferraro	ITPA Joint Experiment :	No
Description:		ITER IO Urgent Research Task :	No
Experimental Approach/Plan:	The 'H-mode compass scan' technique developed during the 2011 TBM campaign will be applied to these new 3-D field configurations. The plasma target will be identical to that of the 2011 TBM experiment so that the results from the two may be compared. The reference shot is 147135, with beta_N = 1.8, q95=4.1. The technique consists of ramping the coil amplitude at 4-5 different toroidal phases. During the ramps the total angular momentum, plasma response, and plasma-wall Maxwell stress will be measured. A fit to these parameters will determine the optimum amplitude and phase for a given metric. To test the combined algorithm, the degree of rotation braking with each individual optimum current will be compared to the total optimum current, as long as the required currents are within the limits of existing power supplies. The experimentally derived optima will then be compared to calculations of both resonant and NTV braking from IPEC, M3D-C1, or other plasma response codes. The anti-kink field should produce dominantly NTV braking, while the kink field should be dominantly resonant. This experiment could be accomplished in 10-11 good shots.
Background:	Optimal error field correction of n=1 fields is now thought to be a competition between two potentially exclusive goals - the minimization of both resonant braking (which is dominantly induced by kink-resonant edge fields) and the global NTV braking due to non-resonant (and kink-resonant) fields. Experiments up to now have exclusively used 3D field spectra that contain elements of both, that is, their poloidal spectrum is both kink-resonant and non-resonant. This experiment will attempt to look directly at the relative importance of kink-resonant and non-resonant fields at braking the plasma in the high-beta scenario where this is most important, as well as and develop control algorithms which minimize both as much as possible.
Resource Requirements:	beta_N control and injected torque control are critical. All 3D power supplies (4 SPAs, 2Cs) will need to be available. A patch panel change will likely be necessary during the experiment.
Diagnostic Requirements:	SXR, CER, MSE, Thomson, 3D magnetics
Analysis Requirements:	TRANSP runs for all discharges, normal suite of 3D field analysis tools.
Other Requirements: