The spatial distribution of deuterium neutrals in the divertor chamber of tokamaks and their dynamics play a key role in achieving detached divertor conditions, the mode of operation foreseen in ITER, and in enabling particle (density) control via pumping. In present tokamaks, neutrals due to recycling of plasma ions at plasma-facing components are also one of the main sources of particles in the core plasma, and thus considered to impact the pedestal density and to lead to power losses in the core due to charge exchange with plasma ions. The physical divertor geometry and plasma configuration are key parameters in confining neutrals within the divertor. In particular, vertical target (VT) configurations are considered to better confine neutrals than horizontal configurations as recycling neutrals are preferentially released in the direction of the separatrix and private flux region.

Preprint of Paper to be submitted for publication in Proceedings of the 40th EPS Conference on Plasma Physics, Espoo, Finland 1st July 2013 - 5th July 2013