Modification of the carbon and beryllium walls in JET by erosion, redeposition and deuterium trapping after the 1991 discharge period
After plasma operation in 1991 samples were cut from C and Be tiles of the JET vessel walls, limiters, and X-point tiles along a poloidal cross-section in octant 4W, and the surface layers were analysed by the MeV-ion beam methods NRA, PIXE and RBS to determine the D and metal impurity distributions. The amount of trapped deuterium ranges from 5 x 1.0 E15 to 5 x 1.0 E17 D/cm2, metal impurities such as Ni, Cr and Fe are in the range of 1.0 E15 to 3 x 1.0 E16/cm2, Cl in the range of 1.0 E16 to 1.0 E18/cm2, K and Ca in the range of 1.0 E15 to 1.0 E16/cm2 and Ti about 1.0 E15/cm2. Except for Cl, all measured concentrations are lower (by a factor as high as ten), than those observed on JET wall tiles before Be evaporation and Be wall components were used. This observation is in agreement with the reduced impurity concentrations measured in the JET plasma. The D and impurity distributions along the X-point tiles were analysed in some detail. Generally, the deuterium trapping and impurity deposition show minima at areas where erosion dominates, and in between these areas the amounts found can be larger by a factor of about ten.
Bibliographic Reference: Report: JET-P(93)92 EN (1993)
Availability: Available from Max-Planck-Institut für Plasmaphysik, 8046 Garching bei München (DE)
Record Number: 199410026 / Last updated on: 1994-11-28
Original language: en
Available languages: en