DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2013 EXPERIMENTAL CAMPAIGN Review | Direct submission with log-in | Request submission without log-in
Print this page

Print this page
Title	311: Transport with qmin>2
Name:	Christopher Holcomb holcomb@fusion.gat.com	Affiliation:	Lawrence Livermore National Laboratory
Research Area:	Steady State Heating and Current Drive	Presentation time:	Not requested
Co-Author(s):	Ferron, Heidbrink	ITPA Joint Experiment :	No
Description:	This proposal adds to ideas presented in Heidbrink's ROF #39. Scan various quantities and make good diagnostic measurements to clarify the reasons for poor energy confinement in plasmas with qmin>2. After identifying the best conditions for confinement in controlled scans, apply maximum power to test betaN limit.	ITER IO Urgent Research Task :	No
Experimental Approach/Plan:	Standard double null shape. Bt=+1.75 T. Flattop betaN=2.7. In all scans obtaining FIDA, neutrons, standard profiles (n, T, etc), and fluctuation data is a high priority. 1. 2 point scan in qmin (~1.5, 2.1) at fixed q95 to recover H89 trend with qmin. 2. Then 3 pt. scan in q95 (4.5, 5.5, 6.5) with qmin=2.1. 3. Density scan with fixed q. 4. 2 pt. ECCD deposition scan with fixed q.(maybe?) 5. Scan rhoqmin out by starting with max Bt and ramping down to Bt=1.75 T at one value of q95. 6. Identify best conditions for confinement and maximize betaN with qmin>2.
Background:	Plasmas with off-axis NBI, ECCD, and qmin>2 in 2011 & 2012 typically had H89<2, making access to betaN>4 with the available power difficult. Indirect evidence suggests enhanced fast ion transport occurs at the highest qmin. Thermal transport is likely also affected, but questionable ne and Te measurements mean considerable uncertainty remains. No FIDA or thermal turbulence measurements were made. Several shots with Bt-ramps to broaden the current profile did have periods of time with qmin>2 and H89>2, but it is unclear if this was due to the q-profile (i.e. increased volume of low shear) or lack of ECCD because of low field operation.
Resource Requirements:	All NBI except 210lt. Ability to go to higher power. 150 at max tilt angle. Consistent gyrotron power at least 3 MW. Clean machine.
Diagnostic Requirements:	MSE, TS, ECE, CER, Spred FIDA! Neutrons Desire Reflectometer Desire fluctuation diagnostics (PCI, ECEI, polarimeter, DBS, etc.)
Analysis Requirements:
Other Requirements: