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	118: Dominant electron heated ITER baseline scenario studies
Name:	Francesca Turco turcof@fusion.gat.com	Affiliation:	Columbia University
Research Area:	Inductive Scenarios	Presentation time:	Requested
Co-Author(s):	J. Hanson, G. Jackson, T. Luce, J. Navratil, W. Solomon	ITPA Joint Experiment :	No
Description:	The goal of this experiment is to study the performance and the MHD stability of the dominant electron heated ITER baseline scenario. These discharges would have all the ITER-relevant characteristics reproduced together for the first time: q95=3.1, betaN~1.8-2.2, low li, low/zero rotation, and Te>Ti (expected Te/Ti~>1.15). It is necessary to assess the performance and the MHD stability of this scenario with few or zero fast particles, and transport properties characteristic of electron heating. We propose to explore the betaN-li-torque-Te/Ti stability map with the methods that have proven effective in the past 2 DIII-D ITER campaigns, as well as to assess the effects of EC heating and current drive in different depositions on the plasma cross-sections.	ITER IO Urgent Research Task :	No
Experimental Approach/Plan:	a.Reproduce shot #150840, with all 6 gyrotrons (3.5 MW of ECH?), q95=3.2 (instead of q95=4.2), no FW, no pellets, possibly with no NBI power (the target shot had 1 MW of NBI). If necessary (i.e betaN too low?), add progressively enough beam power to sustain betaN>~1.8 without H-to-L back transitions. b.Scan the initial li (varying the Ip ramp rate) to assess if there is a ??preferred? state less prone to developing tearing instabilities. Scan Te/Ti adding NBI power with balanced injection (keep rotation as constant as possible). Scan Te/Ti with co-injection, obtain rotation scans. How fast can the current be ramped (i.e. how low an li can be obtained), before an RWM sets in? Can this boundary be changes adjusting the beam power or the ECH power location? c.Move part of the ECH power to ECCD off-axis to tailor the current profile and make it more tearing stable.
Background:	A significant amount of work has been done to characterize the low-torque ITER b.s. scenario, which uses counter-NBI sources to lower the plasma rotation. The current profile evolution was found to be the main actuator to affect the tearing stability of the discharges. betaN, li and torque scans were performed to map the stability space, and at the end of the campaign a series of discharges were attempted, which used full power ECH (central radial injection), and various amounts of beam power (1-2.5 MW total). Since MHD stability was a problem at q95=3.1 and the focus of the experiment was not on obtaining precise ITER-like conditions, the discharges were moved to a safer q95=4.2 value. It is now time to move to the more challenging, but also more relevant, q95=3.2 value, and assess if and how discharges can be run under Te>Ti conditions, with dominant electron heating. This experiments is needed to seek answers to questions such as -Is the li-betaN-torque stability map different from the one obtained with dominant beam power? -How fast can the current be ramped (i.e. how low an li can be obtained), before an RWM sets in? -Can this boundary be changes adjusting the beam power or the ECH power location?
Resource Requirements:	30 and 330 NBI sources, both 210 NBI sources. 6 gyrotrons at max power and max duration.
Diagnostic Requirements:	Magnetics, MSE and CER when NBI usage allows, Thomson scattering, ECE radiometer, density interferometer
Analysis Requirements:	--
Other Requirements:	--