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	115: QH-mode at low co-Ip torque using n=2 NRMF
Name:	Keith Burrell Burrell@fusion.gat.com	Affiliation:	General Atomics
Research Area:	Inductive Scenarios	Presentation time:	Not requested
Co-Author(s):	M.J. Lanctot	ITPA Joint Experiment :	No
Description:	The goal of the experiment is to determine whether using nonaxisymmetric fields from the C-coil wired for n=2 gives improved QH-mode operation at low co-Ip torque. These data will also be used as a test of NTV torque theory.	ITER IO Urgent Research Task :	No
Experimental Approach/Plan:	Create QH-mode shots similar to 149220 but with the C-coil connected in the n=2 configuration. The I-coil will be used for error field correction. Scan neutral beam torque in the stationary phase of the shot to determine the maximum co-Ip NBI torque which can be used. Compare this to results from 149217-221 to see the change in peak NTV torque. Vary the toroidal phase of the n=2 field to examine the importance of the intrinsic n=2 error field. To see how different n-numbers combine, add as much even parity n=3 field as possible from I-coil while maintaining good n=1 error field correction
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. The most recent results showed that NRMF from the C-coil alone allow operation at co-Ip torque up to about 1 Nm; scaled to ITER, this is 3 times the NBI torque that it will have. The goal of the present experiment is to investigate the effect of wiring the C-coil with an n=2 configuration. Due the coil geometry, the n=2 configuration has toroidal sidebands, namely a significant n=4 magnetic field at roughly 50% of the n=2 field. The resulting multi-harmonic field may lead to increased NTV torque over the n=3 configuration, which creates a relatively pure n=3 field.
Resource Requirements:	Reverse Ip. C-coil configured for maximum n=2 field, 7.1 kA current. I-coil configured for error field correction and possible even parity n=3 NRMF.
Diagnostic Requirements:	Standard profile and all fluctuation diagnostics, especially edge BES and ECE-I for EHO studies
Analysis Requirements:
Other Requirements: