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P: Fachverband Plasmaphysik

P 18: Poster: Theorie/Modellierung

P 18.14: Poster

Wednesday, April 1, 2009, 17:30–19:30, Foyer des IfP

Towards a Better Understanding of Critical Ion Temperature Gradients in Tokamaks — •Julian Hüser¹, Frank Jenko², and Rudolf Friedrich¹ — ¹Institut für Theoretische Physik, WWU Münster — ²Max-Planck-Institut für Plasmaphysik, D-85748 Garching, Germany

It is well known that tokamaks often exhibit ion temperature profiles whose gradients are close to the threshold of ion temperature gradient (ITG) modes. Thus, the ratio of the core to edge ion temperature is directly linked to the radial profile of this critical value. Since about 2000, it is also known that nonlinear effects can lead to a significant upshift of the threshold, an effect called Dimits shift. However, to date, the physics underlying this phenomenon is not well understood. The present work attempts to shed new light on the Dimits shift effect by means of nonlinear gyrokinetic simulations with the GENE code (www.ipp.mpg.de/∼fsj/gene) along with dynamical systems analyses of the simulation data.