Features of changes in the surface structure of K-208 glass under electron—proton irradiation

Abstract

Changes in the surface structure of K-208 glass after single-time irradiation of its samples with 20-keV electrons and protons are studied using atomic-force microscopy. Irradiation is performed in a vacuum chamber under a pressure of 10–4 Pa; the densities of the electron (ϕ e ) and proton (ϕ р ) fluxes are varied in the range of 1010–2.5 × 1011 cm−2 s−1. Analysis of the samples irradiated in the case where the parameters ϕ e and ϕ р increased in a stepwise manner makes it possible to study the appearance, growth, and evolution of microscopic structures on their surfaces. The radiation-stimulated processes of defect annealing and the release and field diffusion of alkali metal ions are accompanied by crystallization of the irradiated glass layer, which gives grounds for the use of dislocation mechanisms for mass transfer in explaining the formation of microprotrusions on its surface. It is shown that the character of changes in the structure is determined by the values of the parameters ϕ e and ϕ р and the ratio between them. In particular, it is established that, in the case of electron— proton irradiation of the glass, electrostatic discharges begin to noticeably affect the formation of microprotrusions for ϕ е > 3ϕ р .