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	80: Poloidal spectral measurements of n=3 RMP ELM suppression using the 3D magnetics upgrade
Name:	Josh King kingjd@fusion.gat.com	Affiliation:	Department of Energy
Research Area:	ELM Control	Presentation time:	Requested
Co-Author(s):	E.J. Strait and M.E. Fenstermacher	ITPA Joint Experiment :	No
Description:	Use new 3D magnetics upgrade to measure suspected changes in the inner wall poloidal spectrum associated with n=3 RMP ELM suppression.	ITER IO Urgent Research Task :	Yes
Experimental Approach/Plan:	By modifying collsionality, generate identical discharges with and without ELM suppression to study differences in mode structures. Apply an n=3 RMP. C-coil EFC may be useful to maximize the ELM suppression window. Maintain high βN (~2.2) in initial discharges to maximize 3D signal. Fixed parameters needed for successful 3D magnetics measurement: βN, shape, I and C-coil amplitudes, and q95. Also, variations in the overall q-profile should be minimized. In all cases the I-coils will need to oscillate in phase by 600 for synchronous detection. High Collisionality: (1) ELM suppression shot: Apply an oscillating, odd parity n=3 RMP and maintain suppression through I-coil 600 phase shifts (2) Loss of ELM suppression shot: Reduce ν < 1.0 while maintaining βN constant by reducing density (stronger pumping), and increasing temperature (stronger NBI). Low Collisionality: (1) ELM suppression shot: Apply an oscillating, even parity n=3 RMP and maintain suppression through 600 phase shifts (2) Loss of ELM suppression shot: Increase ν > 0.4 while maintaining βN constant by increasing density (weaker pumping), and decreasing temperature (weaker NBI). After achieving both high and low collisionality cases at high βN, scan to lower βN until suppression is completely lost.
Background:	It is hypothesized that there is a change in the poloidal spectrum associated with the transition of an applied RMP to an ELM suppressed state. For example, does the perturbation become more or less ballooning-like during ELM suppression? This experiment aims to answer such questions.
Resource Requirements:	2 bi-polar SPAs to drive an oscillating n=3. 3 SPAs to drive the C-coil.
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 needed.
Other Requirements: