EDS gave the relative mass concentration of impurities trapped in the carbon-deposited
layer and, in particular, has allowed to identify a boron-rich carbon sub-layer. Specific
measurements were done on both sides of the thin boron layer observed at ~100 µm (Fig.
5). Before the boronisation, carbon and iron concentration are respectively 78% and 13%,
whereas they are respectively 91 % and 3 % after boronisation. These results have been
confirmed by ToF-SIMS analysis performed on the same sample (Fig. 6). In Fig 6,
boronisation can be seen as a boron peak located at 140 µm from the CFC/carbon layer
interface. The impurity profiles show a decrease after this peak whereas hydrogen and
carbon signals increase (the carbon profile will not be discussed here)