  The scrape-off layer parallel heat flux decay lengths measured at ST40, a
high field, low aspect ratio spherical tokamak, have been observed to bifurcate
into two groups. The wide group matches closely with the scale of ion poloidal
Larmour radius and follows existing H-mode scalings, while the narrow group
falls up to 10 times below scalings, on the scale of ion total Larmour radius.
The onset of the narrow scrape-off layer width is observed to be associated
with suppressed magnetic fluctuations, suggesting reduced electromagnetic
turbulence levels in the SOL.
