Improved confinement with counter neutral injection into ASDEX

Abstract

Counter injection into ASDEX leads to good particle, momentum, and also energy confinement with ${\ensuremath{\tau}}_{E}$=80 ms at 1 MW (43 ms for co-injection). The improved confinement develops gradually during the heating phase and correlates with a simultaneous peaking of the density profile. The ion heat transport has to be reduced for a consistent transport analysis, in agreement with theoretical expectations. The sawtooth instability flattens the density profile and transiently reduces the energy content.