1. EX/9-4: Erosion, Screening, and Migration of Tungsten in the JET Divertor
Quasi-steady-state conditions in JET-ILW:
151 consecutive self-similar H-mode plasmas
significant W erosion of about 1.5 µm in 900s
intra-ELM sputtering ~70% (by D and Be ions)
inter-ELM erosion ~30% (by Be ions)
ERO
Tungsten erosion/deposition balance:
net erosion: g (post mortem analysis)
gross erosion: g (tungsten spectroscopy)
high W prompt re-deposition fraction: >90%
ERO code confirms >95% re-deposition
Tungsten migration and screening:
majority of gross eroded W deposited nearby
geometrical screening in pump duct possible
transport to remote areas during ELMs ?
W sputtering and hydrogenic isotopes: D-> T
intra-ELM sputtering will rise by min a factor 3
inter-ELM sputtering by T ions possible