E. S. Mashkova

Particle and energy reflection from solid surfaces

Abstract Experimental and theoretical studies as well as computer simulations of particle and energy reflection coefficients which are of interest to fusion research are reviewed.

Sputtering of solicon and germanium by middle-energy heavy ions

Abstract The angular and energy dependences of the sputtering ratios of silicon and germanium targets under bombardment by argon ions of ten-keV energy are studied.

Directional effects of the molecular ion reflection from a crystal surface

Abstract The reflection of 30 keV molecular N+2 ions from the (100) face of copper crystal has been studied experimentally. Under the examined experimental conditions, the yield of the reflected molecular ions has been found to sharply increase when the primary ion incidence plane gets parallel to the axis of the surface semichannels formed by the close-packed atomic rows of a single-crystal target. The magnitude of the effect is more than 15 times as high compared with random orientation of the primary beam with respect to the irradiated crystal target.

On a new method of observing defects annealing in crystals

Abstract A simple convenient method based on the use of ion impact phenomena is proposed for studying the kinetics of the annealing of defects.

A mechanism of ion scattering by crystals

Abstract On the basis of new experimental data a simple qualitative mechanism of ion scattering by crystals is proposed.

The features of molecular ion dissociation for ion reflection from a copper single-crystal surface

Reflection of 30 keV molecular nitrogen ions from a (100) copper crystal face is studied for a variety of experimental geometries. The dependence of the ion intensity on the azimuthal angle of target rotation throughout the variation interval of glancing angles studied is much stronger for molecular ions reflected without dissociation compared with the dissociated ions.

Effect of surface semichanneling on energy distributions of molecular ions reflected from single-crystal surface

Abstract Regularities in the energy distributions of molecular nitrogen ions reflected from (100)Cu crystal face are studied. The half-widths (FWHM) of the energy distributions of the reflected ions have been found to vary strongly near aligned orientations of the target with respect to the bombarding ion beam. A relationship has been found between the survival fraction of reflected molecular ions and the effect of ion focusing in surface semichanneling.

Energy distributions of fast ionized recoils

Abstract The angular and energy distributions of fast ionized recoils produced under both single-crystalline and polycrystalline copper bombardment by 10–35 keV energy noble gas ions have been investigated. The distributions have been found to be strongly affected by regular arrangement of the target atoms. The obtained results are discussed in terms of the simple models of the process.

Spatial and energy distributions of ions scattered by crystal

Abstract A sharp anisotropy of spatial and energy distributions of ions scattered by crystal has been observed.

Erosion of Carbon-Based Materials Under High-Fluence Heavy-Ion Irradiation

Carbon-based materials are widely used in aerospace industry due to their strength, heat shielding properties, and a number of other specific characteristics [1]. To trace the radiation damage influence on the erosion regularities the sputtering yields Y of highly-oriented pyrolytic graphite (HOPG), polycrystalline graphites and one-dimensional composite material under high-fluence (10 – 10 ion/cm) 30 keV N2 and Ar ions at the incidence angles from θ = 0 (normal incidence) to θ = 80, developed morphology and crystalline phase state from low temperatures (T ~ −180C) till elevated ones (T ~ 400C) have been studied. At normal and near normal ion incidence Reflection High Energy Electron Diffraction has shown that diffraction patterns correspond to a high degree of disorder (diffuse halo) at the temperatures less the defect annealing temperature Ta. At elevated temperatures (T > Ta) the patterns have been found similar to those for the non-irradiated surfaces. It has been found that Ta is easy determined by a step-like behavior of a temperature dependence of ion-electron emission yield γ. This γ-jump has been explained by the dependence of secondary electron path length λ on changes in lattice structure (transition from strongly disordered surface layer under ion irradiation at T Ta) [2]. The Y(θ) dependences measured at T Ta, due to the ion-induced diffusion processes, causing three-fold suppression of sputtering in comparison with irradiation at T < Ta. The Ar irradiation at the room temperature results to strong sputtering suppressing in comparison with the isotropic polycrystalline graphites at the same conditions.