Application of a low intensity repetitive laser for modification of material properties

This paper describes optimizations of laser ion source for applications in ion implantation and for ablative removal of fuel trapped in co-deposited layers on a surface of in vessel tokamak components. In the Institute of Plasma Physics and Laser Microfusion (IPPLM) have been performed extensive studies of implantation of laser-produced Ge ions into a layer of semiconductor materials. The stream of Ge ions was controlled with the use of ion diagnostics. These investigations have demonstrated essential changes of properties of implanted semiconductor (e.g. formation of Ge nano-crystals in a surface layer of SiO2). This same repetitive laser system has been applied in IPPLM also for removal of co-deposited layer from surface of in-vessel components taken from in-vessel tokamak components containing deuterium. The key effort was made for the characterization of ionic species emitted from the laser-ablated co-deposits from the sample surface. The main parameters of laser-produced co-deposit plasma were measured in dependences on number of laser shots using ion diagnostics and optical spectrometry. The optical spectroscopy was confirmed as a convenient diagnostics method for the ablative laser removal of the co-deposit layer from the in-vessel tokamak components. The spectroscopy results were fully consistent with results of ion diagnostic measurements and post-mortem analyses of modified samples