D del-Castillo-Negrete et al 2004 Plasma Phys. Control. Fusion 46 A105 doi:10.1088/0741-3335/46/5A/011
D del-Castillo-Negrete, B A Carreras and V E Lynch
Show affiliationsWe study the radial structure of high confinement modes in a simplified, one-dimensional model of the self-consistent interaction of fluctuations, shear flow, and pressure gradient. The model describes the plasma edge with an energy flux coming from the core, which is used as a boundary condition for the pressure transport equation. As the energy flux increases, there is an L–H transition bifurcation which is described near marginal instability using a reduced Ginzburg–Landau model for the shear flow coupled to a transport equation for the pressure. For higher values of the energy flux, a second transition takes place in which the H-mode exhibits a finite-k instability. Numerical results show that this instability leads in the nonlinear regime to the spontaneous formation of a pedestal in the pressure profile, where the effective diffusivity exhibits a sharp drop. A further increase in the energy flux leads to multiple pedestals across the simulation domain.
52.40.Hf Plasma-material interactions; boundary layer effects
52.25.Gj Fluctuation and chaos phenomena
52.30.-q Plasma dynamics and flow
52.35.-g Waves, oscillations, and instabilities in plasmas and intense beams
Issue 5A (May 2004)
Received 11 October 2003
Published 5 April 2004
D del-Castillo-Negrete et al 2004 Plasma Phys. Control. Fusion 46 A105
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