Testing of beryllium marker coatings in PISCES-B for the JET ITER-like wall

Beryllium has been chosen as the first wall material for ITER. In order to understand the issues of material migration and tritium retention associated with the use of beryllium, a largely beryllium first wall will be installed in JET. As part of the JET ITER-like wall, beryllium tiles with marker coatings are proposed as a diagnostic tool for studying the erosion and deposition of beryllium around the vessel. The nominal structure for these coatings is a ∼10 μm beryllium surface layer separated from the beryllium tile by a 2–3 μm metallic inter-layer. Two types of coatings are tested here; one with a nickel inter-layer and one with a copper/beryllium mixed inter-layer. The coating samples were deposited by DC magnetron sputtering at General Atomics and were exposed to deuterium plasma in PISCES-B. The results of this testing show that the beryllium/nickel marker coating would be suitable for installation in JET.