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M. Willensdorfer, E. Wolfrum, A. Scarabosio, F. Aumayr, R. Fischer, B. Kurzan, R. McDermott, A. Mlynek, B. Nold, S. Rathgeber, V. Rohde, F. Ryter, P. Sauter, E. Viezzer, . ASDEX Upgrade Team:
"Electron density evolution after L-H transitions and the L-H/H-L cycle in ASDEX Upgrade";
Nuclear Fusion, 52 (2012), 1140261 - 11402610.

The development of the electron density profile and its dependences after the L-H transition have been investigated.
Only electron cyclotron resonance heated H-modes have been analysed to exclude core particle fuelling. While
the density gradient in the edge transport barrier increases significantly after the L-H transition, the pedestal top
temperature rises continuously with the applied heating power and shows no pronounced change at the transition.
The H-mode density saturates at a level which correlates with the neutral gas density in the divertor prior to the
L-H transition. Although the density build-up varies with the available deuterium inventory, the initial increase
in the edge density gradient is similar. This has been observed independent of the L-mode plasma collisionality
(ν
∗ ≈ 2.8-5.5). The analysis of electron density and temperature profiles reveals that L-H and H-L transitions
occur at similar pedestal top pressures, but the pedestal top densities are always higher at the time of the H-L back
transition.