  Due to their high cross-field mobility, neutrals can contribute to momentum
transport even at the low relative densities found inside the separatrix and
they can generate intrinsic rotation. We use a charge-exchange dominated
solution to the neutral kinetic equation, coupled to neoclassical ions, to
evaluate the momentum transport due to neutrals. Numerical solutions to the
drift-kinetic equation allow us to cover the full range of collisionality,
including the intermediate levels typical of the tokamak edge. In the edge
there are several processes likely to contribute to momentum transport in
addition to neutrals. Therefore, we present here an interpretive framework that
can evaluate the momentum transport through neutrals based on radial plasma
profiles. We demonstrate its application by analysing the neutral angular
momentum flux for an L-mode discharge in the ASDEX Upgrade tokamak. The
magnitudes of the angular momentum fluxes we find here due to neutrals of up to
$1{-}2\;\mathrm{N\, m}$ are comparable to the net torque on the plasma from
neutral beam injection, indicating the importance of neutrals for rotation in
the edge.

Plasma Physics