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	62: RMP assisted snowflake divertor
Name:	Oliver Schmitz oschmitz@wisc.edu	Affiliation:	University of Wisconsin
Research Area:	Divertor & SOL Physics	Presentation time:	Requested
Co-Author(s):	T.E.Evans et al.	ITPA Joint Experiment :	No
Description:	Application of 3D field - for instance n=3 fields for ELM control - have to be shown to lead to striation of the divertor particle and heat fluxes. These striations are caused by the decomposition of the stable and unstable manifolds of the separatrix. Recently direct imaging confirmed this structure formed due to the divertor X-point as hyperbolic fixed point. In the snowflake configuration a secondary X-point is generated which in the snowflake + configuration is located inside of the wall. This configuration is prone to a strong interaction of the manifolds of both hyperbolic fixed points. This is likely to facilitate opening of the magnetic field region at the separatrix and distribution of the heat and particle outflux into many lobes born from both X-points. In addition, the high magnetic shear in the plasma edge facilitates island overlap and stochastization which can be beneficial for pedestal stability control. Investigation of the impact of snawflake configuration with RMP fields on edestal stability and the transient and stationary divertor fluxes is proposed in this experiment.	ITER IO Urgent Research Task :	No
Experimental Approach/Plan:	- Setup optimized snowflake + configuration (e.g. 149736 at 3750 ms) - Apply RMP field from I/C-coils - scan mode number and RMP strength - measure heat and particle fluxes in divertor - measure pedestal profiles - investigate divertor conditions AND pedestal stability
Background:	This experiment makes use of the unique 3D coil capabilities of DIII-D and the flexibility of PCF and field coils for generating snwoflake. The results can enhance the snowflake divertor concept and may show an improved method to control edge stability and transients in snwoflake configuration
Resource Requirements:	One day at DIII-d, snowfalke patch panel, Icoils on SPAs, C-coils for EFC
Diagnostic Requirements:	divertor IR divertor visible cameras (DiMeS TV and TTV) with D_a, and CII, CIII - soft X-ray at Xpoint with low and high energy cut off filters - edge Thosmson scattering
Analysis Requirements:	- pre experiment: explore with TRIP-3D field structure (ongoing),explore impact on edge transport with EMC3-Eirene (grid modification required for snowflake) - post experiment: TRIP3D and EMC3-Eirene, EPED/ELITE for pedestal stability
Other Requirements:	--