Tokamak edge (scrape-off layer) plasmas can exhibit non-local transport in
the direction parallel to the magnetic field due to steep temperature
gradients. This effect along with its consequences has been explored at
equilibrium for a range of conditions, from sheath-limited to detached, using
the 1D kinetic electron code SOL-KiT, where the electrons are treated
kinetically and compared to a self-consistent fluid model. Line-averaged
suppression of the kinetic heat flux (compared to Spitzer-Harm) of up to 50% is
observed, contrasting with up to 98% enhancement of the sheath heat
transmission coefficient, γe​. Simple scaling laws in terms of basic SOL
parameters for both effects are presented. By implementing these scalings as
corrections to the fluid model, we find good agreement with the kinetic model
for target electron temperatures.
It is found that the strongest kinetic effects in γe​ are observed at
low-intermediate collisionalities, and tend to increase at increasing upstream
densities and temperatures. On the other hand, the heat flux suppression is
found to increase monotonically as upstream collisionality decreases. The
conditions simulated encompass collisionalities relevant to current and future
tokamaks.Comment: 24 pages, 14 figure