One of the first studies of MAST Upgrade divertor configurations with
SOLPS5.0 are presented. We focus on understanding main prospects associated
with the novel geometry of the Super-X divertor (SXD). This includes a
discussion of the effect of magnetic flux expansion and volumetric power losses
on the reduction of target power loads, the effect of divertor geometry on the
divertor closure and distribution of neutral species and radiation in the
divertor, the role of the connection length in broadening the target wetted
area. A comparison in conditions typical for MAST inter-ELM H-mode plasmas
confirms improved performance of the Super-X topology resulting in
significantly better divertor closure with respect to neutrals (the atomic flux
from the target increased by a factor of 6, but the atomic flux from the
divertor to the upper SOL reduced by a factor of 2), increased radiation volume
and increased total power loss (a factor of 2) and a reduction of target power
loads through both magnetic flux expansion and larger volumetric power loss in
the divertor (a factor of 5-10 in attached plasmas). The reduction of the
target power load by SXD further increases with collisionality (high density or
detached regimes) thanks to larger importance of volumetric power losses. It is
found that a cold divertor plasma leads to stronger parallel temperature
gradients in the SOL which drive more parallel heat flux, meaning that the
effectiveness of perpendicular transport in spreading the power at the target
can be reduced, and this needs to be taken into account in any optimisation.Comment: 32 pages, 23 figures. This is an author-created, un-copyedited
version of an article accepted for publication in PPCF. IOP Publishing Ltd
and IAEA are not responsible for any errors or omissions in this version of
the manuscript or any version derived from i
