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	220: Comparison of n=2 RMP field effects on ELMs and pedestal properties in KSTAR and DIII-D
Name:	Todd Evans evans@fusion.gat.com	Affiliation:	General Atomics
Research Area:	ELM Control	Presentation time:	Not requested
Co-Author(s):	YM Jeon, J. Kim, Y. Oh, J. Kwak, W. Kim, JY Kim. et al., and ITPA PEP-23+25 Group Members	ITPA Joint Experiment :	Yes
Description:	In 2011 KSTAR obtained ELM suppression using n=1 RMP fields but did not see suppression when using n=2 fields. In November 2012 ELM suppression was observed with n = 2 fields and the n = 1 results were reproduced with a longer suppression window and better density control. The goal of this experiments is to match as closely as possible, in DIII-D, the operating parameters used in n=2 ELM suppression experiments at KSTAR during 2012 and apply similar RMP fields. If ELM suppression is obtained we will vary the I-coil and discharge parameters to test the boundaries of the suppression window (e.g., I-coil current, q95, Pinj and shape). This data will be used as part of a worldwide n = 2 RMP study to quantify the parameters required for ELM suppression versus ELM mitigation with a variety of coil geometries and plasma conditions.	ITER IO Urgent Research Task :	Yes
Experimental Approach/Plan:	Start with a plasma and RMP fields that are relatively well matched to to those used in KSTAR for their n=2 RMP experiments. Attempt to suppress ELMs with a Br spectrum, density, Pinj, and pedestal profiles similar to those in KSTAR. Acquire high resolution profile data with and without n=2 RMP fields and compare the differences with those seen at KSTAR. Adjust the RMP field plasma parameters until relatively long ELM suppressed conditions are obtained. Establish the boundaries on beta normal, rotation, density/collisionality, and q95 for good n=2 suppression and identify regions of ELM suppression parameter space that are compatible with KSTAR operations.
Background:	KSTAR has obtained n=1 and 2 ELM suppression with a significantly different type of RMP coil and plasma parameters than in DIII-D with either the n=2 or n=3 I-coil RMP fields. In addition, attempts to obtain ELM suppression in DIII-D with n=1 fields have not yet resulted in suppression or significant mitigation. Understanding the mechanisms involved in ELM suppression between the two machines will provide new insight into the key physics mechanisms involved in ELM suppression. Joint experiments between DIII-D and KSTAR can result in a rapid expansion of our ability to predict how the ITER ELM coils will behave and how best to optimize RMP coil designs to suppress ELMs while minimizing negative effects on H-mode performance and divertor operations.
Resource Requirements:	PCS shape control algorithms compatible with KSTAR shapes in addition to the standard RMP ELM control hardware and heating systems (NBI, ECH and ICRF).
Diagnostic Requirements:	Standard RMP ELM control diagnostics.
Analysis Requirements:
Other Requirements:	Scheduling of the experiment needs to accommodate the travel arrangement of the international participants.