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The behaviour of the density profiles in ASDEX Upgrade can be described well with the assumption D alpha {chi} and a pinch of the order of the neoclassical Ware pinch. The latter is estimated from slowly equilibrating density profiles. The assumption D alpha {chi} has been successfully tested by varying the heat deposition profile, making use of on-/off-axis ICRH and ECRH: due to the generally observed self-similarity of the temperature profile, such variations in the heat flux profile have a strong effect on the chi-profile and on the D-profile if the above assumption is correct. The corresponding variations in the density profiles have indeed been observed. The model is also capable of describing the decay of the density profile after injecting a train of pellets. The anomalous transport of impurities is also increased with central heating, and the corresponding flattening of the density profile leads to a significant reduction of the neoclassical impurity pinch. Central ICR or ECR heating are therefore now routinely used to control density peaking and its negative effect on the stability of neoclassical tearing modes as well as to control the impurity transport in ASDEX Upgrade.

Additional information

Authors: LORENZINI R, Consorzio RFX, Associazione Euratom-ENEA sulla Fusione, Padova (IT);STOBER J, Max-Planck-Institut für Plasmaphysik, IPP-EURATOM Association, Garching (DE);DUX R, Max-Planck-Institut für Plasmaphysik, IPP-EURATOM Association, Garching (DE);GRUBER O ET AL, Max-Planck-Institut für Plasmaphysik, IPP-EURATOM Association, Garching (DE)
Bibliographic Reference: An article published in: Nuclear Fusion 43 (October 2003) 1265-1271
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Record Number: 200317198 / Last updated on: 2003-12-02
Original language: en
Available languages: en