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	120: Optimizing non-resonant, nonaxisymmetric fields in QH-mode
Name:	Keith Burrell Burrell@fusion.gat.com	Affiliation:	General Atomics
Research Area:	Inductive Scenarios	Presentation time:	Not requested
Co-Author(s):	M.E. Fenstermacher, M.J. Lanctot	ITPA Joint Experiment :	No
Description:	The goal of this experiment is to determine whether the poloidal mode structure of the nonaxisymmetric fields affects the NBI torque that can be used to sustain QH-mode plasmas with small or co-Ip NBI torque. The experiment allows the poloidal spectra to be ordered according to the net torque, thereby providing a test of plasma response and NTV theory.	ITER IO Urgent Research Task :	No
Experimental Approach/Plan:	Reproduce QH-mode shot similar to 141436, which used I-coil for NTV and C-coil for error field correction. Use torque ramp during stationary phase of discharge to determine NBI torque limit. Vary phase between upper and lower rows of I-coil to determined phase dependence of this limit. Include single row cases to evaluate the benefits of multi-row coil systems for rotation control in future devices.
Background:	QH-mode is an extremely attractive operating mode for future devices, since it exhibits H-mode confinement combined with steady-state operation without ELMs. Work in the 2009-2012 campaigns on D III-D has demonstrated QH-mode operation with zero-net NBI torque or small co-Ip torque by replacing the NBI torque with torque from neoclassical toroidal viscosity produced using nonresonant n=3 magnetic fields. Unfortunately, with the present D III-D set of nonaxisymmetric coils, there is no way to alter the poloidal mode spectrum. If we use an n=2 configuration for the I-coil, we can continuously adjust the phase between the upper and lower rows of the I-coil, thus altering the poloidal mode spectrum. For example, the spectrum can be adjusted so it is neither pitch resonant nor kink resonant.
Resource Requirements:	Reverse Ip. C-coil configured for n=1 error field correction. I-coil configured for n=2 with the upper and lower rows independently powered.
Diagnostic Requirements:	Standard profile and all fluctuation diagnostics, especially edge BES and ECE-I for EHO studies
Analysis Requirements:
Other Requirements: