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Progress in Plasma Processing of Materials, 2003

ISBN:
978-1-56700-192-1 (Print)
978-1-56700-447-2 (Online)

ENTRAINMENT OF AMBIENT AIR INTO AN ARGON ICP

Marco J. van de Sande
Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands

P. van Eck
Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands

Antonio Sola
Departamento de Fisica Aplicada, Universidad de Cordoba, 14071 Cordoba, Spain

Antonio Gamero
Departamento de Fisica Aplicada, Universidad de Cordoba, 14071 Cordoba, Spain

Joost J. A. M. van der Mullen
Department of Applied Physics, Eindhoven University of Technology, P. O. Box 513, 5600 MB Eindhoven, The Netherlands

Abstract

Entrainment of air molecules into spectrochemical ICPs, which are normally operated in the open air, may influence the plasma's behaviour, especially so at its edge. In this study, the air concentration and temperature just outside the plasma were measured by rotational Raman scattering. The electron density and temperature inside the plasma were determined by Thomson scattering. By using both techniques simultaneously and with spatial resolution, positioning errors are kept to a minimum. Just within the torch, but outside the plasma region, the gas temperature is well below 1000 K and the air concentration is less than 10%. No region where both electrons and air were present in detectable amounts (1019 and 1024 m−3 respectively) was observed. This suggests that air entrainment does not play a significant role in the plasma dynamics of the ICP, perhaps with an exception at the outermost boundary.