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Title	232: Bifurcated helical core equilibrium - continued
Name:	Oliver Schmitz oschmitz@wisc.edu	Affiliation:	University of Wisconsin
Research Area:	Stability & Disruption Avoidance	Presentation time:	Requested
Co-Author(s):	W.A.Cooper, B. Tobias, E. Lazarus, A. Turnbull, F. Turcon, T. Evans, L. Lao, M. Lanctot, O. Sauter	ITPA Joint Experiment :	No
Description:	Approach tackling to generate a bifurcated helical core equilibria from another standpoint - based on lessons learned during half day Torkil Jensen Award experiment in 2012. The experiment will be enhanced by looking into edge vs. core response. Recent ANIMEC modeling including RMP modes similar to the spectrum used for ELM control have shown a strong deformation at the edge with maintaned helical core. This can be an advantegeous scenario for ITER hybrid discharges.	ITER IO Urgent Research Task :	No
Experimental Approach/Plan:	Run highly elongated plasma with q_0 slightly above unity. Control broad q-profile by off axis ECCD and generate flat or best hollow q-profile with q_min at large radius. Let q profile evolve to lower q_0 from above 1 (which was not accomplished/attempted in initial experiment) to allow helical core take over before sawteeth set in.
Background:	In 2012 a Torkil Jensen Award experiment was executed in an international collaboartion to generate a bifurcated helical core plasma. The experimental sequence was based on ANIMEC modeling of 3D equilibria. We got a transient state with a long liced core mode which exhibits properties of the helical core, saturated kink like mode we are expecting. However, this mode occured only transiently and we concluded as a reason that we have to adapt the experimental strategy in two major points: (1) in order to achieve a q_0 at unity without letting sawteeth dominating the scene, we have to generate a plasma whcih drifts into q_0 around unity from above. (2) the plasma we run were L-mode plasmas with moderate elongation. These plasmas are not good for effective ECCD due to low edge temperatures and hence weak CD efficiency. To enhance this we need to attempt the experiment in H-mode. Last, we saw that increased elongation is beneficial and hence we want to run an H-mode plasma at increased elongation. Key is to get a flat or best even hollow q profile with q_o at unity avoiding sawteeth before q_0 goes towards this level.
Resource Requirements:	ECH for ECCD (all gyrotrons) Highly elongated plasma (last time we used DN patch) H-mode in HFS limited configuration of maybe DN
Diagnostic Requirements:	toroidal and poloidal soft X-ray arrays ECE-I Xpt soft Xray imaging n=3 in 240 degree phasing from Icoils and standard setup for ELM control
Analysis Requirements:	ANIMEC kinetic EFITS
Other Requirements:	--