Far scrape-off layer particle and heat fluxes in high density – High power scenarios
Abstract The far scrape-off layer transport is studied in ASDEX Upgrade H-mode discharges with high divertor neutral density N 0 , div , high power across the separatrix P sep and nitrogen seeding to control the divertor temperature. Such conditions are expected for ITER but usually not investigated in terms of turbulent SOL transport. At high N 0 , div and P sep the H-mode discharges enter a regime of high cross-field particle and power transport in the SOL which is accompanied by a significant change of the turbulence characteristic analogous to the transition from conductive to convective transport in L-mode. Parallel particle and power flux densities of several 10 23  m−2 s−1 and 10 MW m−2 have been detected about ∼40 to 45 mm outside the separatrix mapped to the outer mid-plane. The particle flux fall-off length reached up to 45 mm. This paper presents for the first time an empirical condition to enter the high transport regime in H-mode and the relation of this regime to changes in the filamentary transport.