Far scrape-off layer particle and heat fluxes in high density - High power scenarios

The far scrape-off layer transport is studied in ASDEX Upgrade H-mode discharges with high divertor neutral density N-0,N-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,N-div and P-sep the H-mode discharges enter a regime of high cross-field particle and power transport in the SQL 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 similar to 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. (C) 2015 Elsevier B.V. All rights reserved.