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Edge profiles of electron temperature and density are measured in ASDEX Upgrade with a high spatial resolution of 2�3 mm with Thomson scattering. In the region of the edge transport barrier in ELMy H-mode, the gradient lengths of T(e) and n(e) are found closely coupled, with the temperature decay length two times shorter than the density decay length corresponding to eta(e) approximately equals 2. The eta(e) constraint allows us to calculate the electron temperature and density profiles from the pressure profile if the density and temperature values are known at one spatial position. The edge density in the region of the barrier foot is closely coupled to the main chamber recycling, with no strong dependence on other parameters. In contrast, the density rise from the outer barrier foot to the pedestal exhibits pronounced dependence on plasma current and shaping, indicating quite different mechanisms determining the absolute density and its gradient.

Additional information

Authors: KALLENBACH A ET AL, Max-Planck-Institut für Plasmaphysik, EURATOM Association, Garching (DE)
Bibliographic Reference: An article published in: Nuclear Fusion 43 (July 2003) pp. 573-578
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