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P: Fachverband Plasmaphysik

P 3: Magnetischer Einschluss

P 3.2: Vortrag

Montag, 19. März 2007, 11:30–11:45, 6F

Self Consistent Nonlinear Burst Phenomena in Tokamak Edge Turbulence — •Bruce Scott — Max-Planck-IPP, Euratom Association, Garching, Germany

Tokamak edge turbulence is studied using three dimensional computations within low frequency gyrofluid and gyrokinetic models. The entire background, including the confining magnetic field, is carried self consistently. The density and temperature profiles are maintained by particle and heat sources. The particle source is either set at the interior (pellet or beam fuelling) or arises from a simple neutral gas fuelling/recycling model. When the temperature gradient is steepened by increasing the heat source, global scale bursts occur in the transport. The diagnosis indicates breakdowns in the equilibrium flow structure as the cause. Analysis of the threshold criteria is given. The transition from a quiescent to bursty transport state with increasing power reflects low and high power L-Mode transport in the tokamak edge and is quantitatively realistic. The status of the search for a self consistent H-Mode trigger, reflecting the sharp improvement of confinement above a power threshold in real tokamaks, will be reported at the conference. Progress in gyrokinetic computation of these phenomena will also be reported.