Transport Barrier in the Edge of the Chaotic Reversed Field Pinch (Abstract/Comunicazione in atti di convegno)

Type
Label
  • Transport Barrier in the Edge of the Chaotic Reversed Field Pinch (Abstract/Comunicazione in atti di convegno) (literal)
Anno
  • 2005-01-01T00:00:00+01:00 (literal)
Alternative label
  • G.Spizzo; A.Cravotta; S.Cappello; D.F.Escande*; I.Predebon§; L. Marrelli; P. Martin; R.B.White#; A.Canton; F. Auriemma; R.Lorenzini; P.Zanca (2005)
    Transport Barrier in the Edge of the Chaotic Reversed Field Pinch
    in 2005 Transport Task Force Meeting, Napa, California, USA, Apr 6, 2005 - Apr 9, 2005
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • G.Spizzo; A.Cravotta; S.Cappello; D.F.Escande*; I.Predebon§; L. Marrelli; P. Martin; R.B.White#; A.Canton; F. Auriemma; R.Lorenzini; P.Zanca (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#url
  • https://wormhole.ucllnl.org/TTF2005/dbms/abs/abs47.pdf (literal)
Note
  • Abstract (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • Consorzio RFX, EURATOM-ENEA Association, Padova, Italy *UMR 6633, CNRS-Université de Provence, Marseille, France §Present address: University of the Punjab, Lahore, Pakistan # PPPL, Princeton, NJ, USA (literal)
Titolo
  • Transport Barrier in the Edge of the Chaotic Reversed Field Pinch (literal)
Abstract
  • Magnetic field lines and the corresponding particle orbits are computed for a typical chaotic magnetic field provided by a magnetohydrodynamics (MHD) numerical simulation of the reversed-field pinch (RFP). The numerical simulations are obtained through the three dimensional code SpeCyl [ ], while the guiding-centre motion is calculated using the ORBIT code [ ] , starting as input with the magnetic field profiles given by SpeCyl. The m=1 modes are phase-locked and produce a toroidally localized bulging of the plasma which increases particle transport, and which is a preferential, super-diffusive channel for particle loss. In the region far from the bulging, the m=0 and m=1 modes produce magnetic chaos implying poor confinement. However they also produce magnetic islands which induce transport barriers in the chaotic sea inside the reversal radius. This has been highlighted computing the loss time of thermal particles deposited in the core, and collected at increasing distances towards the wall. The loss time profile shows a steep gradient at a typical radius smaller than that related to magnetic field reversal. The effectiveness of this transport barrier has been studied in different plasma conditions, in terms of equilibrium parameters (F=/B?(a), being B? the toroidal component of magnetic field), collisions, and amplitude and phases of m=0 and m=1 modes. In particular, starting from simulations, we have studied the scaling of an average particle diffusion coefficient as a function of the m=0 amplitude. These results (i.e., presence of a transport barrier in the proximity of the reversal radius, and the scaling law of particle diffusivity) are in agreement with the transport analyses performed on experimental density profiles of different RFP experiments, that show a clear effect of m=0 modes on the particle diffusion. The possible applications to the Padua RFX experiment, where the effectiveness of the barrier might be changed by varying amplitude and phases of the m=0 modes through the new toroidal power supply system [ ], are also discussed. (literal)
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