Characteristics of the Pulse-Periodic Gas-Generating Source of Flows of Ultraviolet Radiation and Silver Sulphide Microstructures

The research results on the synthesis conditions of surface microstructures of silver sulphide from the plasma of an overvoltage nanosecond discharge (OND) between electrodes made of polycrystalline Ag₂S compound in helium are presented. The discharge is ignited in atmospheric pressure helium with a 2 mm-gap between the electrodes. Silver sulphide vapours are introduced into the He–Ag₂S gas–vapour mixture by means of the ectonic mechanism. The voltage pulses, current, pulsed discharge power, and energy input into the plasma per pulse are studied at pulse repetition frequencies of 40–1000 Hz. Spectral and spatial characteristics of the OND are analysed. Using micro-Raman spectroscopy of laser radiation scattering, the Raman scattering spectra of thin films deposited from the OND plasma onto a quartz substrate located near the electrode system are investigated and analysed. Based on solving the stationary Boltzmann kinetic equation for the electron-energy distribution function, numerical modelling is performed for the plasma transport parameters, specific energy losses, and rate constants of electron processes as functions of the parameter E/N, where E is the electric-field strength, and N is the total particle concentration in the working mixture. The discharge can be utilized as a source of bactericidal radiation, a source of silver sulphide microstructures, and as a plasma-chemical reactor for synthesizing corresponding thin films.