  The guiding-center kinetic neoclassical transport code, XGC0, [C.S. Chang et.
al, Phys. Plasmas 11, 2649 (2004)] is used to compute the heat fluxes and the
heat-load width in the outer divertor plates of Alcator C-Mod and DIII-D
tokamaks. The dependence of the width of heat-load fluxes on neoclassical
effects, neutral collisions and anomalous transport is investigated using the
XGC0 code. The XGC0 code includes realistic X-point geometry, a neutral source
model, the effects of collisions, and a diffusion model for anomalous
transport. It is observed that width of the XGC0 neoclassical heat-load is
approximately inversely proportional to the total plasma current $I_{\rm p}$.
The scaling of the width of the divertor heat-load with plasma current is
examined for an Alcator C-Mod discharge and four DIII-D discharges. The scaling
of the divertor heat-load width with plasma current is found to be weaker in
the Alcator C-Mod discharge compared to scaling found in the DIII-D discharges.
The effect of neutral collisions on the $1/I_{\rm p}$ scaling of heat-load
width is shown not to be significant. Although inclusion of poloidally uniform
anomalous transport results in a deviation from the $1/I_{\rm p}$ scaling, the
inclusion of the anomalous transport that is driven by ballooning-type
instabilities results in recovering the neoclassical $1/I_{\rm p}$ scaling. The
Bohm or Gyro-Bohm scalings of anomalous transport does not strongly affect the
dependence of the heat-load width on plasma current. The inclusion of anomalous
transport, in general, results in widening the width of neoclassical divertor
heat-load and enhances the neoclassical heat-load fluxes on the divertor
plates. Understanding heat transport in the tokamak scrape-off layer plasmas is
important for strengthening the basis for predicting divertor conditions in
ITER.
