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	257: Transport Investigation During Slow Current Ramp-Up and Ramp-Down [for ITER]
Name:	George McKee mckee@fusion.gat.com	Affiliation:	University of Wisconsin
Research Area:	Inductive Scenarios	Presentation time:	Not requested
Co-Author(s):	G. Jackson, T. Casper, D. Mikkelsen	ITPA Joint Experiment :	Yes
Description:	Ascertain the evolution of turbulence, electron temperature and current density profiles during ITER-similar ramp-up and ramp-down plasmas.	ITER IO Urgent Research Task :	No
Experimental Approach/Plan:	Establish ITER-similar plasmas (ISS shape) and equivalent ramp-rates (similar to Jackson experiments from a couple years ago). It will be critically important to obtain thorough documentation of turbulence and transport (esp. Te) profiles during the ramp-phases, from as low an Ip as feasible. This will require a neutral beam (150 L or R), derated as necessary, with full MSE-documentation (may require repeat, reproducible discharges for full diagnostic coverage)
Background:	Accurately modeling the profile evolution during the current ramp-up and ramp-down in ITER will be critical to control and performance. Recent work (Jackson, Casper et al.) have shown discrepancies between models of plasma temperature evolution during current ramp up/down experiments on DIII-D. The electron temperature was observed to be modestly cooler than predicted (Casper-NF-20??), and current diffusion correspondingly faster. This is important to stabile operation and control of the the poloidal field supplies. The dynamics of the how profiles evolve will thus be important to the providing the proper ohmic power. This discrepancy has general similarities with the observed "L-mode shortfall", whereby transport simulations underpredict heat fluxes and turbulence and thus over-predict temperatures. This problem may be exacerbated at high q95, just the conditions during ramp-up. The dynamic evolution of the coupled temperature, turbulence and current density will be critical and thoroughly documented in this experiment. This is an ITPA-relevant topic and of strong interest to ITER (or should be.)
Resource Requirements:
Diagnostic Requirements:	BES, DBS, PCI, CECE, ECEI, ECE, CER, MSE
Analysis Requirements:	TGLF
Other Requirements: