Tungsten coatings under high thermal loads in JET and Magnum-PSI

During the C28–C30 campaigns the ITER-like wall (ILW) was periodically inspected by an in vessel inspection system without breaking the vacuum. After these campaigns the JET chamber was opened and the wall was inspected with a high resolution camera. The marker tiles were removed from the chamber and were inspected in the beryllium handling facility. The overall picture of the ILW after more than 3000 pulses looks good. However there are a few modifications such as the deposition of Be on some W coated tiles, local destruction of the W coating by runaway electrons in an emergency shutdown, arcing on particular W coated tiles, and small delaminations on G6 and G8 divertor tiles. These aspects, together with the results of high heat flux tests carried out with W coated carbon fiber composite samples in Magnum-PSI, are discussed in the paper.