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Title	108: Comparison of main ion and impurity rotation velocity
Name:	Richard Groebner ()	Affiliation:	General Atomics
Research Area:	Rotation Physics	Presentation time:	Not requested
Co-Author(s):	--
Description:	Measure toroidal and poloidal rotation for main ions and impurities. Compare the profiles to determine what the differences are, particularly in the H-mode pedestal.
Experimental Approach/Plan:	Produce H-mode discharges in helium plasmas. Measure the toroidal and poloidal rotation profiles for main helium ions and for impurity carbon ions. Take particular care to measure in pedestal region. Perform density scan to vary collisionality and coupling between the two species.
Background:	Edge rotation may play an important role in a number of phenomena: L-H power threshold, RWM threshold, RMP physics and edge confinement. Edge rotation is also of interest in studies of the generation and transport of intrinsic rotation. At the present time, measurements of edge rotation are made from impurities. However, near the edge, it is likely that the impurity rotation is not always a good proxy for the main ion rotation. There were direct measurements showing this in DIII-D in the mid-90s (published by J. Kim). Thus, it is important that main ion and impurity rotation be compared near the plasma edge so that we can obtain ideas about the limits of usefulness of impurity rotation.
Resource Requirements:	6 NB sources, including the counter beamline.
Diagnostic Requirements:	TS CER CO2 interferometer
Analysis Requirements:	Generate edge poloidal and toroidal rotation profiles for impurities and main ions. Compare any differences in rotation velocity to theoretical predictions, such as those from NCLASS.
Other Requirements:	--