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	138: SSI target improvement by minimizing global low-n MHD activity in 1.5 <q_min < 2 regime
Name:	Michio Okabayashi mokabaya@pppl.gov	Affiliation:	Princeton Plasma Physics Laboratory
Research Area:	Steady State Heating and Current Drive	Presentation time:	Not requested
Co-Author(s):	Francesca Turco, Chris Holcomb, John Ferron, Tim Luce	ITPA Joint Experiment :	No
Description:		ITER IO Urgent Research Task :	No
Experimental Approach/Plan:	Here, assuming that the plasma condition is close to the physics operational limit. - Homework: systematic numerical study of optimizing internal kink limit condition with fixed boundary condition (Francesca Turco has started). The main parameters are geometrical characteristics, flatness of q_min, and off-NBI energy/angle. This process is similar to that as done for classical fishbone. - Experiments: Tight coupling to the wall (forcing modes onset to internal mode) and increasing the triangularity within the limit of proper divertor functions. Fast low-n feedback should be seriously pursued. These low n modes are likely to be just marginally stable, but, the magnitude was amplified by the resonant field amplification through uncorrected error field. If we take this hypothesis, fast DEFC should be applied. The fast time constant should be useful for mode above marginal condition. The feedback on one particular mode can not bring ultimate universal solution, but, careful categorization of level of achievement on feedback parameters will lead to determine the next step toward better SSI operation even q_min>2 configurations.
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