  Measurements of the poloidal electron density and temperature distribution in
the W7-X island divertor reveal the existence of two distinct scrape-off layer
transport regimes. At low and intermediate densities, $T_e$ profiles across the
magnetic island are hollow, with a minimum at the island O-point. Above a
threshold density $\overline{n}_e \approx 5 \times 10^{19}$ m$^{-3}$, the local
minimum vanishes and the $T_e$ profiles become monotonic. At the lowest studied
densities, the hollow $T_e$ profiles imply an electrostatic field of up to
$\textbf{E}_r \sim 6$ kV/m, which can induce $\textbf{E} \times \textbf{B}$
drifts around the island, with drift velocities of up to $\sim3$ km/s. These
$\textbf{E} \times \textbf{B}$ drifts result in strong convective heat
transport poloidally around the island, binormal to the magnetic field, which
supports the hollow radial temperature profile and hence provides a positive
feedback to the electric field. Above the threshold density, these drifts
strongly diminish, presumably due to increased anomalous diffusion, which
causes the profile hollowness and therefore also the radial electric field to
strongly diminish. This argument is supported by comparison to EMC3-EIRENE
modeling and an analytical transport analyses showing that an additional,
non-diffusive transport channel is required to maintain the profile hollowness
up to the densities seen in experiment, and that a poloidal drift transport
channel supports such hollowness only up to certain densities.
