Process control of a plasma treatment of wool by plasma diagnostics

Wool was treated in a large-volume microwave plasma source SLAN II [D. Korz ec, F. Werner, R. Winter, J. Engemann, Scaling of microwave slot antenna (S LAN): a concept for efficient plasma generation. Plasma Sources Sci. Techno l. 5 (1996) 216-234] to improve the felting tendency. To control this plasm a process, the applicability of three plasma diagnostic methods, optical em ission spectroscopy (OES), double Langmuir probe measurements (DLP) and mas s spectrometry (MS), was investigated. The plasma is composed of a variety of species like electrons, ions, neutrals and excited atoms, radicals and m olecules. Many of these may have to be taken into account for a successful treatment of the wool. OES data, which are monitoring excited particles sho w large fluctuations in the line intensities. The main reason for this is t hat the pressure does not remain constant during the plasma treatment. DLP measurements suffered the same problem. Additional problems occurred becaus e the probe surface became contaminated during the measurement. In contrast , the relative intensities of mass lines obtained from quadrupole mass spec trometry (MS) turned out to be a good indicator for the intensity of the pl asma treatment of wool. (C) 1999 Elsevier Science S.A. All rights reserved.