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	23: RMP ELM Suppression at q95 above 4
Name:	John deGrassie degrassie@fusion.gat.com	Affiliation:	General Atomics
Research Area:	ELM Control	Presentation time:	Not requested
Co-Author(s):		ITPA Joint Experiment :	No
Description:	Use shaping to get out of the rut of n=3 RMP ELM suppression in DIII-D only for q95 < 4. Start with the odd parity high q95 (> 7) suppression (mitigation?) LSN condition and lower q95 by reducing the plasma cross section whilst maintaining field line alignment with the two row I-coils on the outside.	ITER IO Urgent Research Task :	No
Experimental Approach/Plan:	The starting condition is n=3 odd parity I-coil suppression (mitigation?) above q95 ~ 7 (e.g. 128464). Vary the plasma q95 value while maintaining alignment of the outboard field lines with the two row I-coil set, by reducing the plasma cross section. Obtain RMP ELM suppression in the range 4 < q95 < 5 in this fashion.
Background:	*With fixed RMP coils and essentially a fixed shape (ITER-like) the suppression, or non-suppression conditions have been established. Ultimately suppression coils should be designed for a specified equilibrium. As yet we do not know how to do the best such design. *Understanding how to vary the q95 windows is necessary to gaining this design capability. *This technique has been used, albeit by luck, in shot 122445, with a skinny LSN and odd parity I-coils that resulted in suppression (mitigation?) in the range 4 < q95 <6. *At higher q95 the mitigation phenomenon may be more at work than that of suppression, using Chapman's explanation (APS Invited 2012), and that is why MAST results are described by mitigation. *Mitigation may be the best tool for ELM control if the resultant energy dumps are at the tolerable level.
Resource Requirements:	One day. Standard RMP ELM suppression experiment.
Diagnostic Requirements:
Analysis Requirements:
Other Requirements: