Heat transport in the JET scrape-off layer

The DIVIMP/NIMBUS onion skin model (OSM) has been used to calculate 2-D plasma distributions of n(e), T-e and T-i in the JET edge, based on boundary conditions measured across the targets with built-in Langmuir probes. Ohmic, L mode and ELMy H mode discharges were analysed. From the calculated 2-D plasma profiles, values of chi(perpendicular to)(SOL)(r) were extracted as a function of radial location within the SOL, showing that chi(perpendicular to)(SOL)(r) increases with radius. At the separatrix chi(perpendicular to)(SOL)(0) was in the range similar to 0.05-1 m(2).s(-1), with the lowest values occurring for H modes (between ELMs). It was found that chi(perpendicular to)(SOL)(r) similar to [T-eu(r)](-2) where T-eu is the electron temperature at the 'upstream' end of the SOL flux tube. No clear correlation with the magnetic field, B-T, was found. The results are not consistent with Bohm (chi(perpendicular to)(SOL) proportional to T-eu/B) scaling.