The Topography of Surface and Light Transmission by Quartz Windows after Exposure in a High-Frequency Discharge in Deuterium and Mixture of Deuterium with Nitrogen

Abstract

The effect of a high-frequency discharge on the change in the topography of the surface of KU-1 optical quartz and transmission of visible light (400–1000 nm) is studied. The working gases of the discharge are D2 and a D2/N2 mixture, in which the fraction of N2 is 25 mol %. The addition of nitrogen increases the rate of sputtering from 60 to 300 nm/h without changing the stoichiometry of the surface layers. After the exposure in plasma, the root-mean-square roughness of the surface decreases from 1.3 to 0.6 nm. The transparence of quartz remains unchanged. The analysis of the roughness and calculation of the diffuse light scattering with a wavelength of 400 nm after passing through quartz are executed using the power spectral density functions.