Khasanshin R.H.,Kompozit Joint Stock Company |
Novikov L.S.,Moscow State University |
Korovin S.B.,RAS A.M. Prokhorov General Physics Institute
Journal of Surface Investigation | Year: 2016
Electrostatic discharges obtained upon the irradiation of K-208 glass with 40-keV electrons at a flux density φ of 1010 to 2 × 1011 cm–2 s–1 are studied. The residual pressure pv in the vacuum chamber is varied from 5 × 10–5 to 5 × 10–3 Pa. Structural changes in the sample surfaces are studied by atomic-force microscopy. Depending on the pressure level, two types of discharges are observed in experiments at 3 × 1010 ≤ φ ≤ 1.2 × 1011 cm–2 s–1: a microprojection at the glass–ionized-residual-atmosphere surface and a discharge which develops along the irradiated surface. It is found that at 5 × 10–5 ≤ pv ≤ 3 × 10–4 Pa and 8 × 1010 ≤ φ ≤ 1011 cm–2 s–1, discharges of the first type appear at the beginning of exposure; that is, an increase in microprojections is observed. Further, surface discharges propagate through these microprojections. At 10–3 ≤ pv ≤ 5 × 10–3 Pa and 1010 ≤ φ ≤ 5 × 1010 cm–2 s–1, on the contrary, discharges of the second type are realized at the beginning. These discharges result in the appearance of channels with inhomogeneities on the glass, at which subsequently discharges of the first type occur. It is determined by calculations that in the region adjacent to the exposed glass surface, secondary electrons accelerated in a field of charge accumulated in the glass make the main contribution to the ionization of gases. © 2016, Pleiades Publishing, Ltd.