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(EX/C3-7Rb) Dependence of Particle Transport on the Heating Profile in ASDEX Upgrade

J. Stober1), R. Dux1), O. Gruber1), L. Horton1), C. Maggi1), F. Meo1), R. Neu1), J.-M. Noterdaeme1), P. Lang1), R. Lorenzini2), A. Peeters1), G. Pereverzev1), F. Ryter1), A.C.C. Sips1), A. Staebler1), H. Zohm1), ASDEX Upgrade Team1)
1) Max-Planck-Institut für Plasmaphysik, Garching, Germany
2) Consorzio RFX, Padova, Italy

Abstract.  The slow peaking of the density profile for high densities with moderate NBI and its disappearance with central ICRH have been reported at the last IAEA conference in Sorrento. Meanwhile a modell asumming D = 0.1 - - 0.15 . $ \chi_{eff}^{}$ and the Ware-pinch has been used successfully to describe the data. Independently we have proven that the peaking is not due to differences of particle fuelling, since off-axis ICRH also leads to peaked density profiles. With the modification of treating the neoclassical ion-heat-flux separately the model holds also for discharges with lower plasma current and even for the density decay after pellet fuelling. The model is also related to the ECRH density pump-out. The separation of electron and ion chanel at low densities will be addressed. Central heating also increases the anomalous diffusivity of impurity ions which is beneficial for a fusion rector. Also Neoclassical Tearing Modes are more stable with central heating due to the flattening of the density profiles in accordance with the theoretical predictions for the dependence of the bootstrap current on the density gradient.

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IAEA 2003