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	234: Study fishbone-like instability at the edge of QH-modes
Name:	Filomena Nave mfn@ipfn.ist.utl.pt	Affiliation:	Instituto Superior Tecnico, Lisboa, Portugal
Research Area:	Inductive Scenarios	Presentation time:	Not requested
Co-Author(s):	W. Heidbrink, Y. Zhu, K. Burrell, N. Gorelenkov	ITPA Joint Experiment :	No
Description:	(Related research area: Energetic particles) Investigate ehos in the form of chirping modes. Study their interaction with fast ions.	ITER IO Urgent Research Task :	No
Experimental Approach/Plan:	Repeat an old pulse where n=3 chirping eho modes are observed. Use the best diagnostics available for fast particles and fluctuations. The aim is to improve on the data available for existing pulses. Possible reference discharges: pulse 118740 and pulse 131376.
Background:	QH-modes are characterized by the EHO, edge MHD activity that appears to delay ELMs by enhancing transport at the top of the pedestal. In some discharges the EHO appears in the form of repetitive bursts resembling fishbone activity, with typical mode numbers in the range n=3-6. These interesting edge mhd modes were observed in DIII-D QH-mode pulses up to 2008, when the QH-Mode used to be obtained with strong Neutral Beam Injection counter to the plasma current. The chirping nature of the bursts suggests the modes could be driven by NBI fast ions similar to internal n=1 fishbone bursts. Like in the internal fishbones, the eho bursts frequencies are close to the frequency of precession of fast ions. However, whether these edge modes interact with fast ions causing displacement or losses of fast ions remains inconclusive.
Resource Requirements:	Reverse Ip
Diagnostic Requirements:	Fast Particle Diagnostics, fluctuation diagnostics, profile diagnostics
Analysis Requirements:	--
Other Requirements:	--