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	22: Assessment of main chamber carbon sources
Name:	Mathias Groth groth@fusion.gat.com	Affiliation:	Aalto University
Research Area:	Divertor & SOL Physics	Presentation time:	Not requested
Co-Author(s):	Rich Groebner, Tony Leonard, Adam McLean, Max Fenstermacher, Al Hyatt	ITPA Joint Experiment :	No
Description:	Measure core carbon content (n4+ and n6+ carbon densities) as function of inner and outer gap in L-mode	ITER IO Urgent Research Task :	No
Experimental Approach/Plan:	Perform three-point density scan in L-mode (low-recycling, high-recycling close to rollover, detached) with varying gap sizes to inner and outer midplane limiters (while maintaining sufficiently large clearance to upper outer limiter); suggested gap sizes: inner: 12, 6, 3 cm (OMP equivalent), outer 9, 6, 4 cm; ideally vary only one gap while maintaining the others; measure n4+ and n6+ densities in pedestal/SOL regions with CER (= 1 repeat shot per condition); measure low charge state carbon distributions with MDS and tangential cameras
Background:	Previous studies (2004 divertor characterization in L-mode) showed that the core carbon content is insensitive to (a) detachment of the outer divertor and (b) to the gap of the separatrix to the upper outer limiter. Since the inner divertor was detached even in low-recycling conditions, our hypothesis was/is that the main source for carbon in the core is from the inner divertor. To test this hypothesis against other main chamber sources from the inner and outer midplane regions, additional measurements are required.
Resource Requirements:	LSN, fwd BT, L-mode with 1 beam source for edge CER measurements, modulated, co-current; strike points on 45-deg tiles (inner) and shelf (outer) for DTS measurements; variation of inner and outer gaps while keeping other gaps (to top, upper outer limiter) constant
Diagnostic Requirements:	CER for n6+ and n4+ (7270 A) density profiles, divertor and main chamber spectroscopy, tangential cameras, DTS, target LPs, LPs at upper outer limiter
Analysis Requirements:	CER analysis, low charge state carbon profiles from MDS and 2-D reconstructions from tangential cameras
Other Requirements:	--