Induced Carbon Deposition by Local Hydrocarbon Injection into Detached Divertor Plasmas in JET

ABSTRACT. During the detachment experiments of JET in 2007 , just before opening the machine, 1x1022 molecules of 12CD4 were injected to the L-mode plasma at the outer strike point in the centre of the horizontal target (LBSRP). The deposited layers were analyzed post mortem after the removal of tiles. The heaviest local deposition is found immediately upstream of the gas inlet, but to downstream there is a larger area of deposition. In total, 3.7x1020 deuterium atoms were found locally deposited; if in the deposits the mean D/C = 0.4, then about 10% of the injected carbon was locally deposited. Transport and local deposition of the injected carbon was modeled with the 3D Monte Carlo impurity transport code ERO. The plasma background was generated with the onion-skin solver of the DIVIMP code. The toroidal decay of deposition is reproduced with ERO, but the poloidal transport of carbon is several times weaker than measured. The results indicate that re-erosion of the layer during the attached plasma phases has been significant.
Name Size  
EFDC100508 1.50 Mb