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SUMMARY:"Turbulence and its interaction with magnetic topology"
DTSTART:20141107T093000
DTEND:20141107T103000
DTSTAMP:20261002T012315Z
UID:35286a7d028690161dc0a0fdb6773a89a90f83e0b2fd202b977a6b6f
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr. N. Vianello\, Consorzio RFX\, C.so Stati Uniti 4\, Padova\
 , Italy\nThe paradigm of 2D axisymmetry in magnetically fusion devices is 
 being progressively abandoned in favor of a more realistic description of 
 the 3D geometry of the magnetic field. Indeed\, apart from intrinsic 3D co
 nfigurations such as stellarators\, the effects of non-axisymmetric magnet
 ic field are becoming a fundamental issue also for tokamaks\, where magnet
 ic perturbations are used for ELMs control\, and Reversed Field Pinches (R
 FPs)\, with the observation of a spontaneous self organized helical state 
 in high current regimes in. Experimental observations in the RFPs have rev
 ealed that a magnetic island or an edge helical ripple\, generates a three
  dimensional flow pattern as the result of ambipolar constraints and this 
 mechanism is likely to act independently of the configuration.\nThe way a 
 3D field interacts with plasma turbulence is presently a matter of active 
 research. Indeed it is well known that fluctuations carry a substantial fr
 action of particle and energy transport\, in particular in the periphery o
 f confined plasma. In this region transport is dominated by the presence o
 f coherent structure/blobs\, i.e. fluctuations localized in space and time
  which carry energy and particles through their convective motion and/or t
 heir mutual interaction. These structures exhibit the feature of filaments
  elongated in the direction of the magnetic field: the presence of a non a
 xisymmetric magnetic field is believed to modify their properties acting o
 n their source of free energy through the modulation of typical gradient s
 cale length\, their dynamics through the modification of the velocity fiel
 d\, and their characteristics for example through the modification of the 
 parallel connection length. In the present seminar we present an overview 
 of the experimental observations on these processes as obtained in the edg
 e region of RFX-mod experiment\, operated both as a Reversed Field Pinch a
 nd as a tokamak. We will also provide comparison with observations obtaine
 d in other devices.
LOCATION:PPB 019
STATUS:CONFIRMED
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