EFDA-JET-CP(10)05/10

Removal of Beryllium-Containing Films Deposited in JET from Mirror Surfaces by Laser Cleaning

A set of Stainless Steel (SS) and Molybdenum (Mo) mirror samples located in the divertor and at the outer mid-plane of the vessel were exposed in JET from 2005-2007. A selection of these mirror samples with well adhered deposits (i.e. not flaking) of up to a few hundred nanometers in thickness and with Be/C ratios ranging from 0 to ~1 have been cleaned using a laser system developed at CEA, Saclay and the results are reported here. Following laser cleaning the recovered reflectivity was generally better in the infrared than the visible spectrum, with recovery of up to 90% of the initial reflectivity being obtained at 1.6 m for both Mo and SS mirrors falling as low as 20-30% at a wavelength of 0.4m for SS mirrors, rising to ~80% for Mo mirrors. Some deposit remained on the mirrors after the cleaning trials.
Name Size  
EFDC100510 1.23 Mb