Q2. What is the likely cause of erosion during the divertor phase of each ILW?
During the divertor phase of each discharge erosion is probably dominated by charge exchange neutral (CXN) bombardment of the main chamber wall, and is followed by migration along the SOL to the inner divertor.
Q3. What is the purpose of the ITER-like wall project?
After over two decades of JET operation with a carbon wall, the ITER-like wall project at JET (JET-ILW) was initiated to explore plasma performance and plasma-wall interaction processes with a full metal wall: bulk beryllium (Be), Be-coated Inconel in the main chamber and bulk tungsten (W) or W-coated carbon fibre composites (CFC) in the divertor [1, 2].
Q4. What software was used to determine the chemical composition and thickness of deposits?
Experimental data were processed using NDF [10] and/or SIMNRA [11] software to determine the chemical composition and thickness of deposits.
Q5. What is the amount of material deposited on Tiles 4 and 6?
The amount of material deposited on Tiles 4 and 6 was generally below ~2.5·1018 at/cm2, however areas of highier deposition (~6·1018 at/cm2 of Be over the 1 mm2 beam area) were found on the slopping of these tiles.
Q6. What is the effect of surface profilometry on the tiles?
The tiles are relatively clean, however there are traces of W, Ni, Mo, Cr, and Fe on the surface, and NRA shows some D retention.
Q7. What is the likely cause of the erosion at the IWC?
This is evidenced by erosion measurements at the Inner Wall Cladding (IWC) tiles that line the vessel wall between the IWGL [14] which suggest that the IWC may account for a significant fraction of the Be deposition found in the divertor.
Q8. What is the likely cause of erosion on Be tiles?
There are also many areas where widespread arcing has occurred that are visible on Be tiles: such arcing may also be widespread on W-coated CFC tiles but would not be easily visible, however could easily dislodge coating asperities from these rough surfaces.
Q9. What is the contribution of the IWC to the erosion of the vessel?
Some contribution may also be expected from re-erosion of the deposits on the IWGL, which may have a higher erosion yield than the bulk material.
Q10. What is the structure of the deposited material?
combining the information of the BSE microscopy, the SEM analysis and IBA, it can be concluded that the deposited material has a multi-layered structure consisting of an outer layer of pure