High-current heavy-ion accelerator system and its application to material modification

A high-current heavy-ion accelerator system has been developed to realize intense particle fluxes for material modification. The facility of a tandem accelerator attained 1 mA-class ion current both for negative low-energy ions and positive high-energy ions. A negative ion source of the key device is of plasma-sputter type, equipped with multi-cusp magnets and Cs supply. The intense negative ions are either directly used for material irradiation at 60 keV or further accelerated up to 6 MeV after charge transformation. Application of negative ions, alleviating surface charging, enables us to conduct low-energy high-current irradiation to insulating substrates. Since positive ions over MeV are irrelevant to the Coulomb repulsion, the facility as a whole meets high-current irradiation into insulators over a wide energy range. Application of high flux ions provides technological merits not only in efficient implantation but also in different material kinetics. Other characteristics of the system are co-irradiation of intense laser and in-situ detection of kinetic processes. For the material modification, we present nanoparticle fabrication in insulators, and synergistic phenomena by co-irradiation of ions and photons.