[Zurück]

L. Shao, E. Wolfrum, F. Ryter, G. Birkenmeier, F. Laggner, E. Viezzer, R. Fischer, M. Willensdorfer, B. Kurzan, . ASDEX Upgrade Team:
"On the role of the edge density profi_le for the L-H transition power threshold in ASDEX Upgrade";
in: "Proc. 42nd EPS Conference on Plasma Physics, Europhys. Conf. Abstracts", Vol. 39E; EPS Conference on Plasma Physics, 2015, ISBN: 2-914771-98-3, S. 11131 - 11134.

On ASDEX Upgrade, the carbon tiles were replaced stepwise by tungsten (W) plasma
facing components (PFCs) starting from 2003 and ending in 2007 [1]. Since 1999, the so-
called `H-mode standard shot' has been run as the rst plasma discharge of each operation
day at ASDEX Upgrade. The L-H transition is induced by a power ramp of neutral beam
injection (NBI) achieved by beam modulation with increasing duty-cycle. A decrease of the
power threshold (PL􀀀H) of about 25% for the H-mode standard shots was found when the
full tungsten coverage of PFCs was reached [2, 3]. Neoclassical theory predicts that the
edge radial electric eld (Er) is mainly driven by the main ion species [4, 5]. At ASDEX
Upgrade it has been shown that, at xed BT and magnetic con guration, the minimum in the
neoclassical radial electric eld Er;neo at the L-H transition is almost independent of density
in the full tungsten wall [6].