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	379: Pedestal optimization of ITER baseline scenario discharges.
Name:	Thomas Osborne osborne@fusion.gat.com	Affiliation:	General Atomics
Research Area:	Pedestal Structure	Presentation time:	Not requested
Co-Author(s):	P. Snyder, R. Groebner, T. Rhodes, G. McKee, Z. Yan	ITPA Joint Experiment :	No
Description:	Previous work (Osborne APS 2012) has demonstrated a variation in pedestal pressure of up to 50 % can be obtained ITER baseline scenario discharges. In this experiment we would build a better understanding of the reasons for this variation. High pedestal pressures were associated with the build up of pedestal density at low ELM frequency with the pedestal temperature saturated early in the inter-ELM period. This enhanced the pedestal collisionality allowing higher pressure at the peeling mode limit, however the dominate effect was an increase in the pedestal width. In the lowest ELM frequency discharges the width substantially exceeded the EPED1 width prediction. This is in qualitative agreement with the expectation that the KBM stability should be reduced at high collisionality allowing higher pressure at the peeling limit. In the new experiments we would obtain better fluctuation data to determine if the high width discharges are indeed still KBM limited or in fact if some other process has limited the pressure gradient below the KBM threshold. In addition the mechanism for the variation in the ELM frequency and pedestal pressure was not clear from the previous experiment. The build up of high Z impurities or the betan feedback control of the heating power may have played a role.	ITER IO Urgent Research Task :	No
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