EFD-P(13)19 Laser Cleaning of Beryllium- Containing First Mirror Samples from JET and PISCES-B

A set of seven polycrystalline mirror samples retrieved from the JET tokamak have been cleaned in vacuum using a pulsed laser system. The samples were exposed between 2008- 2009 as part of the second phase of a comprehensive first mirror test and contain a mixture of carbon, beryllium and tritium. For this reason, the samples were treated in a vacuum chamber especially constructed for this purpose. Additionally, three samples coated in PISCES-B with a 110-120nm beryllium layer were cleaned as well. The results are quite positive, most mirrors showing a substantial increase of the specular reflectivity after cleaning. The ones that do not appear to have been damaged already prior to cleaning.