Wall conditioning of JET with the ITER-Like Wall

Abstract

The initial conditioning cycle of \{JET\} İLW\} is analysed and compared with restart and operation in 2008 with a carbon dominated wall. Comparable water and oxygen decay times are observed during bake-out in both cases. Despite a 2 × 10−3 mbar l/s leak rate during plasma operation, no further wall conditioning has been necessary after plasma restart in ILW, which dramatically contrasts with 2008. Plasma O content is lower with the ILW. Higher O levels are measured after nights or week-ends, BeO layers being formed and re-eroded, but do not impact plasma operation and performance. First results on isotopic wall changeover by \{GDC\} on the İLW\} six months of the first \{D2\} campaign evidence a reservoir of about 3 × 1022 atoms, i.e. ten time lower than in carbon PFCs. A study in \{JET\} of the glow discharge current distribution for different ratios of the ionization mean free paths to the vessel dimensions seems to indicate sufficient toroidal and poloidal homogeneity in ITER