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	205: SOL width in top-limited discharges
Name:	Dmitry Rudakov rudakov@fusion.gat.com	Affiliation:	University of California, San Diego
Research Area:	Divertor & SOL Physics	Presentation time:	Not requested
Co-Author(s):	R. Pitts (ITER), J. Boedo, A. Leonard, C. Lasnier, G. Jackson, P. Stangeby, R. Moyer, J. Watkins	ITPA Joint Experiment :	No
Description:	Experiments were performed on DIII-D in 2009 to benchmark the assumed ITER SOL power width scaling for startup/ramdown limiter phases. Both the high field side (HFS) and low (LFS) field side startup options are considered for ITER. In DIII-D a good data base of HFS-limited discharges was obtained and used for comparison with the scaling. However, only one good discharge was obtained in the top-limited configuration - the best proxy to a toroidally symmetric LFS-limited configuration available at DIII-D. We propose a 1/2 day experiment designed to complete the LFS-limited part of the data base.	ITER IO Urgent Research Task :	Yes
Experimental Approach/Plan:	Experimental approach will be similar to that used in 2009 experiments. The main diagnostic will be mid-plane reciprocating probe that will be plunged twice in every discharge. Shape and parameters of shot 136595 should be restored, then the shot will be repeated with NBI power going from 0 to 1.1 MW around 3 seconds into the discharge. Plasma current and density will be varied from shot to shot. Some LSN discharges may be run for reference.
Background:	The ITER first wall(FW) is being designed to allow start-up on the actively cooled beryllium panels on both the high (HFS) and low (LFS) field sides, and plasma scenarios have been developed. Power handling is determined by the parallel heat flux density, and the panel shaping. The former is characterized by the SOL power flux density e-folding length lambda_q. ITER presently assumes a modified divertor scaling based mainly on data from JT-60U and JET for lambda_q in the limited phase. Experiments performed on DIII-D did not confirm the functional dependencies on the plasma parameters assumed in the scaling, but most measured values of lambda_q in HFS-limited configuration agreed with the scaling within the assumed uncertainty (a factor of 2). For LFS-limited configuration only one good shot was available, so more data are needed for a meaningful comparison.
Resource Requirements:	1/2 day experiment (~10 documentation discharges). Top-limided Ohmic and L-mode with up to 1.1 MW of NBI.
Diagnostic Requirements:	Mid-plane reciprocating probe, IRTV (if LSN discharges are run), core Thomson, CER, fast UCSD camera, tangential TVs, mid-plane filterscopes, profile reflectometry.
Analysis Requirements:
Other Requirements: