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VERSION:2.0
PRODID:-//Memento EPFL//
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SUMMARY:Magnetic island dynamic with current sheet and turbulence
DTSTART:20130128T103000
DTEND:20130128T113000
DTSTAMP:20260510T053642Z
UID:341c1c5eec93c96ee73d9ad5bc59002a8df7dcbb5d68f77943b5f395
CATEGORIES:Conferences - Seminars
DESCRIPTION:Alexandre Poyé\, Université de Provence\, Marseille\, F\nMag
 netic islands are a source of damage in tokamaks and their control by inje
 ction of external control current requires an ever growing understanding o
 f the physical processes [Commisso et al\, Nucl. Fusion\, 125002 (2010)]. 
 The nonlinear evolution of magnetic islands is investigated by means of nu
 merical simulations.\nFirst\, we show that classical boundary layer analys
 is\, leading to Rutherford like equations\, may not capture the island wid
 th dynamics generated by tearing instability. We underline the importance 
 of the initial global current profile. Indeed\, nonlocal effects of a fini
 te current density away from the resonant surface can significantly alter 
 the island growth and saturation. The underlying mechanisms linked to the 
 generation of vorticity by interacting current sheets\, including island s
 eparatrices\, are presented.\nSecond\, we address the problem of the gener
 ation of seed magnetic islands by turbulence [Muraglia et al\, Phys. Rev. 
 Lett.\, 095003 (2011)]\, which is relevant in NTM context. We show - and p
 resent the different mechanisms at play - that turbulence can spread out i
 nto stable regions where for instance low order rational surface q=2 is av
 ailable and drive the generation of m/n=2/1 island. It gives some support 
 to the observation that magnetic island do appear only at low order ration
 al surface.
LOCATION:PPB 019
STATUS:CONFIRMED
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