Plasma Formation on the Ferroelectric Surface in a Low-Pressure Argon Atmosphere

Abstract

The formation of plasma on the surface of BaTiO₃ ferroelectric ceramics in an argon atmosphere in the pressure range 1 × 10^–5–1 × 10^–2 Torr has been experimentally studied. Based on the discharge voltage and current, the energy supplied by the driving pulse generator for plasma formation was investigated. It is shown that at argon pressures ≥10^–3 Torr, the fraction of energy spent on plasma formation increases significantly due to the growth of the discharge current. The elemental composition of the plasma was examined by optical emission spectroscopy, and the electron temperature and density were determined from analysis of Ar II ion spectral lines, taking into account the optical thin condition of the plasma and the McWhirter criterion. Local thermodynamic equilibrium in the plasma is achieved at argon pressures ≥10^–3 Torr. The dependence of the electron temperature and density on argon pressure has been determined. As the argon pressure increases, the electron temperature rises from 0.8 to 1.2  eV, while the electron density reaches (2‒5) × 10¹⁵ cm^–3. The concentration ratio of argon ions Ar II to Ba II and Ti II ions in the plasma has been determined over the studied pressure range.