Hydrocarbon Film Deposition Inside Cavity Samples in Remote Areas of the JET Divertor During the 1999-2001 and 2005-2009 Campaigns
Hydrocarbon film deposition was studied with cavity samples in remote areas of the inner and outer JET divertor and below the divertor septum during the 1999­2001 and 2005­2009 campaigns. Thick hydrocarbon films were formed inside the cavities. These deposited hydrocarbon layers have high D/C ratios close to 1. The formation of these films is mainly due to sticking of hydrocarbon particles with high surface loss probabilities >0.6. The observed surface loss probabilities depend on the position in the divertor and vary during different campaigns. The particles responsible for hydrocarbon layer formation originate from the divertor strike points. Except for the septum cavity the deposition of beryllium was very low and showed a very different distribution from that of deuterium and carbon.