Monitoring Removal of W Layer from Ag Substrate Using Balmer-α Emission of Backscattered Hydrogen Atoms in Low Density Gas Discharge. Acta Physica Polonica A 138, 643 (2020), ERRATUM

S. Ertmer, O. Marchuk, S. Dickheuer, S. Heuer, P.H. Mertens, M. Rasinski, B. Göths, S. Brezinsek, A. Houben, Ch. Linsmeier, A. Kreter Forschungszentrum Jülich GmbH - Institut für Energie- und Klimaforschung-Plasmaphysik, Partner of the Trilateral Euregio Cluster (TEC), 52425 Jülich, Germany

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The Doppler-Shifted Reflectance Measurements diagnostic is applied for in-situ measurements of a total spectral reflectance of the sample during the transition phase induced by physical sputtering of a layer of tungsten (W) from an silver (Ag) substrate. The sputtering of a 4 mm layer of W is monitored at the Balmer-α line λ0=656 nm with a temporal resolution of 60 s corresponding to a thickness of ~λ0/100 in the absence of other light sources. The sample was exposed to a mixed argon (Ar) and hydrogen (H) gas discharge in the linear plasma device PSI-2, where the Ar+ ions, accelerated by the applied negative potential of -180 V, were intrinsically used for sputtering of the deposited film. The sputtered W or Ag were also monitored by optical emission spectroscopy. It is shown that in low density gas discharges the Doppler-Shifted Reflectance Measurements diagnostic is, in providing the value of reflectance, extremely sensitive to the transition phase between W and Ag - as compared to resorting to the W-I and Ag-I emission lines intensities. It could thus be directly applied to cleaning plasma discharges with the presence of Ar and H or deuterium (D) ions.

DOI:10.12693/APhysPolA.139.170 topics: Balmer lines, sputtering, emission spectroscopy, thin films, line shape