Investigation of JET ITER-like wall Be marker tiles

Abstract

The JET tokamak is operated with beryllium and tungsten plasma-facing components to prepare for the exploitation of ITER. Marker tiles were installed in the limiters and divertor in order to determine the erosion and deposition. Specimens from different Be marker tiles of the ITER – Like wall JET tokamak main chamber and from the exposure periods 2011-2012 and 2013-2014 were investigated using nuclear reaction analysis, X-ray fluorescence spectroscopy and scanning electron microscopy in order to assess the deposition focusing on the C deposition, erosion and surface morphology. Carbon was detected on surface of all the samples, while its surface atomic density and the deposition depth range from (0.35±0.07)×1017 to (11.8±0.6)×1017 at/cm2 and from 0.4 to 6.7 μm, respectively. Tungsten is, also, detected in samples. Finally, partial or strong erosion was observed on the surface of most of the samples, while the morphology of sample surfaces presents significant differences comparing with the reference one.