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	256: Fine scale stepwise q-scan: role of low-order rationales and resonance condition for ELM suppression
Name:	George McKee mckee@fusion.gat.com	Affiliation:	University of Wisconsin
Research Area:	ELM Control	Presentation time:	Not requested
Co-Author(s):	Evans, Nazikian, Wade, Yan	ITPA Joint Experiment :	No
Description:	Determine how transport and turbulence in the near edge region (0.8 < r/a< 0.98) vary as q95 is varied in very small increments inside and outside of the ELM suppression window (q95~3.5), and if and how this affects the ELM-suppression process.	ITER IO Urgent Research Task :	No
Experimental Approach/Plan:	Establish ELM-suppressed plasma conditions, and then ramp q95/Ip in a stepwise fashion to establish quasi stationary conditions at each step. The goal is to perform these steps in and around the ELM-suppression windows in q95, e.g., q95~3.5. A reference condition is 145019, but Ip would not be ramped continuously as it was in these discharges. It will be stepped with delta_q95~0.02-0.05 and held constant for approximately 250 ms at each step to establish a quasi stationary condition for pedestal profiles, and allow for comprehensive documentation of turbulence amplitude and spectra, turbulence and ExB flow profile, and ELM response. BES and DBS would be used to measure turbulence characteristics (150L flat and steady is desired beam configuration, no 150R)
Background:	During q95/Ip ramp discharges in RMP ELM-control experiments, turbulence in the near outer plasma and pedestal region is found to change sharply and locally in response to varying q95. These observations were made with BES covering the 0.8 < r/a < 1+ region and observing temporal variation in local turbulence characteristics. These sharp jumps are sometimes, but not always, associated with changes into or out of ELM-suppressed conditions, and may be associated with low-order rational q95 values in the edge and pedestal region. The plasma profiles and conditions were not stationary and naturally evolved in response to change q95 and ELMing condiion. The goal of this new experiment would be to establish quasi-stationary conditions at each q95 step so that turbulence and profiles could be evaluate in these stationary conditions. The goal would be to raise and lower q95 in steps of about 0.05 near ELM suppression windows and document these changes.
Resource Requirements:	I-coils in standard RMP ELM-suppression configuration: even-parity n=3
Diagnostic Requirements:	BES (8x8), DBS, usual edge profile diagnostics, high-speed CER, UF-CHERS
Analysis Requirements:
Other Requirements: