Internal transport barrier triggered by neoclassical transport in W7-AS.
The three-dimensional magnetic configuration of a stellarator offers two specific mechanisms for a transition to improved particle and energy confinement. One route goes through the so-called electron-root confinement regime, which leads to a reduction of neoclassical transport via strong radial electric fields. In this Letter evidence for a second route is presented. It opens due to the layer of a strongly varying radial electric field which is present in the transitional region from neoclassical electron to ion-root confinement. This type of improvement acts on turbulent transport.
Stroth
U
U
Institut für Experimentelle und Angewandte Physik, CAU Kiel, Germany.
Itoh
K
K
Itoh
S
S
Hartfuss
H
H
Laqua
H
H