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	216: Campaign to study physics at the Greenwald limit
Name:	Egemen Kolemen ekolemen@pppl.gov	Affiliation:	Princeton Plasma Physics Laboratory
Research Area:	Steady State Heating and Current Drive	Presentation time:	Requested
Co-Author(s):	D. Gates, L. Delgado-Aparicio, E. Hollman, J. Ferron, M. Van Zeeland, N. Commaux, B. Tobias, B. Grierson	ITPA Joint Experiment :	No
Description:	There is growing interest at DIII-D physics close to the density limit. A new theoretical model for the Greenwald Limit has been proposed that appears to be consistent with experimental observations based on radiation driven islands by D. Gates. The study of the small pellet injection at the density limit is proposed by N. Commaux. Also, high density allows great conditions for high resolution cameras to study the plasma dynamics (e.g. Van Zeeland visible camera). We propose to make a scenario close to the density limit where all these interesting phenomena can be studied in a combined fashion.	ITER IO Urgent Research Task :	No
Experimental Approach/Plan:	Develop a scenario close to the density limit in which ECH can be deposited without cutoff or too much diffraction. Study all the physics of interest. One prediction of this theory is that direct heating of the rational surfaces that participate in the radiation driven island phenomena should suppress these islands and pass the density threshold, since this would avoid the shielding process described above. 0. Study the effect of the small pellet injection at the density limit. 1. Vary the heating power and location, and measure the island size and radiation a. Run at ECH cut-off density meets Greenwald density limit (~1 MA, 2 T). b. Measure the radiated power from the island to see if the theory predicted power balance criteria is met: High-resolution bolometer for time-resolved profiles of the radiated power density c. Use ECE-I, visible cameras, and MRI to get never before collected data at the density limit to understand the underlying physics of the density limit disruptions. Study the island formation process at different rational surfaces. Note that for high resolution visible camera working at high density will enable good measurements. 2. Seed different impurities (e.g. Argon) a. This will give us better measurement of the island b. Give more information on how the radiation from different species effect the island growth. 3. Look at the effect of heating additional surfaces if the ECH increases the limit.
Background:	--
Resource Requirements:	1-2 days of experimental time.
Diagnostic Requirements:	--
Analysis Requirements:	--
Other Requirements:	--