Properties of the copper surface layers treated by volume gas discharge at atmospheric preassure

This paper presents new experimental data on the properties of the near-surface layers of copper specimens treated by plasma of diffuse discharge. A runaway electron preionized diffuse discharge was formed in air, nitrogen and carbon dioxide at atmospheric pressure by applying of nanosecond high voltage pulses to electrode of small curvature radius. The cleaning from carbon in comparison to the initial sample was observed at a depth exceeding 55 nm. The oxygen concentration was also significantly increased in comparison to that in the initial sample at a depth of up to about 25 nm. It is shown that the nanohardness of copper specimens increased due to interaction of near-surface layers with product of plasma chemical reactions produced in diffuse discharge.