DEVELOPMENT OF LASER PLASMA ABLATION-DEPOSITION TECHNIQUES FOR CARBON STRIPPER FOILS

The aim to develop irradiation resistant carbon stripper foils for swift heavy ions led to the new technique of laser plasma ablation-deposition of carbon, in which a pulsed high power Nd:YAG laser induces a hot carbon plasma for deposition on suitable substrates in high vacuum. The essential physical property of the new technique is the ablation of monoatomic carbon with an average charge state of 4+ and a broad spectrum of energies of up to 1 keV of the monomers. These conditions influence the nucleation and growth of a carbon film in such a way that a nearly isotropic orientation of the nanocrystals in the condensed film is achieved. This results, as postulated, in a much better strength against irradiation damage caused by heavy ions, compared to all other types of stripper foils.