Romanenko O. Ion microbeam formation for study of radiation-induced migration of impurities in a solid

Theoretical and experimental studies performed in the thesis allowed determination of peculiarities of focused ion beam formation that may be used for radiation of the target areas of micron size. Use of a magnet quadrupole lens (MQL) doublet for beam formation with high current density is shown to have some restrictions related to lens aperture dimensions. In the same time, envelope lines of the beams formed by a triplet and a distributed «Russian quadruplet» of MQL do not exceed the ion beam line dimensions. Working distance and focused beam size for the triplet were defined to provide maximum current density. Maximum density for the distributed «Russian quadruplet» of MQL is shown to grow as a working distance and beam spot size grow on a target. A method of the deconvolution of particle distribution at the probe forming system was improved to define the distribution parameters for particles at the PFS entrance and to determine a paraxial brightness of a macrobeam. Performed numerical modeling showed possibility to form the MeV focused beams with current density distribution in a target plane that is close to homogenous current of tens nA. Comparison of theoretical and experimental profiles of secondary emission yield during the sample edges scanning with the beam of preset density has proved evaluation results. A method has been suggested to re-focus the beam while its energy is changed and probe size is preserved within preset limits. Application of the nuclear scanning microprobe in nuclear-physical analytical method is presented for control of samples prepared for radiation-induced migration of impurities in constructional materials.