Characterization of the plasma plume of a PIAD plasma source by means of optical emission spectroscopy

The understanding of the generation of fast ions in the advanced plasma source (APS) is important for the improvement of optical coatings. This requires a detailed characterization of the radial and axial distributions of plasma parameters in the expanding plasma downstream of the APS - the plasma plume. In an industrial vacuum chamber (1.1 m3 volume) diagnostics for optical emission spectroscopy (OES) have been installed. Radial profiles of line emission on an absolute scale are obtained by data deconvolution. First results based on a simple Corona model applied on a Helium-Argon mixture confirm the values obtained by Langmuir probe measurements. In the downstream region of the APS (10 cm-30 cm from its outlet), electron temperatures in the order of 5 to 10 eV and densities of about 1010 cm− 3 are obtained.