Divertor particle and power deposition profiles in JET ELMy H-mode discharges
The transient pulses of heat and particles arriving at the divertor target plates as a consequence of upstream ELM activity have been characterised at JET using an array of target embedded Langmuir probes in the MkIIGB-SRP divertor. High temporal and spatial resolution of the ELM time behaviour has been achieved by slow divertor strike point sweeps during ELMing H-mode discharges and subsequent coherent averaging of the data. One key result is the observation of target particle flux profile broadening with an e-folding length twice the inter-ELM during Type-I ELMs, presumably as a consequence of the enhanced radial transport. During the ELMs large divertor target currents have been observed, which change sign when the direction of the ion B x del B drift is reversed. First comparisons of IR and Langmuir probe derived power deposition profiles have shown a clear increase in the total sheath heat transmission coefficient during the ELMs. (c) 2007 Elsevier B.V. All rights reserved.