HEAT-TRANSPORT AT THE BOUNDARY OF ASDEX UPGRADE

The flow of heat in the scrape-off layer (SOL) region of ASDEX Upgrade is investigated and compared with simple modelling. Parallel heat tra nsport is found to be consistent with electron heat conduction based o n Spitzer-Harm conductivity. Cross-held heat transport is characterize d using radial e-folding distances for power, temperature and plasma p ressure, which are all found to vary weakly over a wide range of disch arge conditions. Type I ELMs, also characterized, introduce a discrete ness to the power flow into the SOL and carry approximately half of th e power exhaust from the discharge. The divertor plates are effectivel y screened from the ELM energy, even in low-radiation discharges, sugg esting enhanced radiation rates during ELMs.