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The transport of silicon has been investigated for various heating scenarios in ASDEX Upgrade H-mode discharges. Inside of r approximately equal to a/4, the diffusion coefficient D is either mainly neoclassical or anomalous depending on the heating method. For all investigated scenarios with NBI-heating and off-axis ECRH or off-axis ICRH, the diffusion coefficient is approximately neoclassical, and the effective heat diffusion coefficient Chi(eff) is below the neoclassical ion heat diffusion Chi(i,neo) in the plasma core. When central ECRH is added, Chi(eff) is above Chi(i,neo), and D strongly increases by a factor of 3�10, i.e. becomes predominantly anomalous. For central ICRH, D is above the neoclassical level by a factor of 2.

For radii outside of r approximately equal to a/4, D is always anomalous and increases towards the plasma edge. For r greater than a/4, we find a clear scaling of D in terms of Chi(eff), where D is about equal or above Chi(eff). A strong inward drift parameter v/D is only observed in the core and only for cases, when the diffusion coefficient is neoclassical. With central wave heating, the drift parameter decreases to small values.

Additional information

Authors: DUX R ET AL, Max-Planck-Institut für Plasmaphysik, IPP-EURATOM Association, Garching (DE)
Bibliographic Reference: An article published in: Plasma Physics and Controlled Fusion, Vol 45 (September 2003), pp.1815-1825
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