Analytical calculation of neutral transport and its effect on ions

The authors present an analytical calculation of the neutral particle distribution and its effects on ion heat and momentum transport in three-dimensional plasmas with arbitrary temperature and density profiles. A general variational principle, taking advantage of the simplicity of the charge exchange (CX) operator, is derived to solve self-consistently the problem of neutral-plasma interaction. To facilitate an extremal solution, the short CX mean-free-path (λx) ordering is used. Furthermore, a non-variational, analytical solution providing a full set of transport coefficients is derived by making the realistic assumption that the product of the CX cross-section with relative velocity is constant. The effects of neutrals on plasma energy loss and rotation appear in simple, sensible forms. It is found that neutral viscosity dominates ion viscosity everywhere, and in the edge region by a large factor