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Influence of Negative Ions on Drift Waves in a Low‐Density Ar/O 2 ‐Plasma
Author(s) -
Knist S.,
Greiner F.,
Biss F.,
Piel A.
Publication year - 2011
Publication title -
contributions to plasma physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.531
H-Index - 47
eISSN - 1521-3986
pISSN - 0863-1042
DOI - 10.1002/ctpp.201000109
Subject(s) - ion , plasma , argon , atomic physics , langmuir probe , excited state , noble gas , oxygen , physics , instability , plasma parameters , materials science , plasma diagnostics , quantum mechanics , mechanics
The effect of negative ions on the drift wave instability has been studied in detail in a linear device by means of Langmuir probes and cross‐correlation analysis. Drift waves are excited in low‐density (5 × 10 14 m –3 ) and strongly magnetized (0.5 T) pure argon plasmas and in the presence of an oxygen admixture. The radial density profile of negative ions is hollow. For increasing concentration of negative ions the wave frequency decreases by about 25%. Despite of an axial density gradient, a global wave frequency is established for the entire column length. While for the noble gas case the drift wave frequency is given by the equilibrium plasma parameters in the mid‐plane, there is no such relationship for the argon plasma with oxygen admixture. This different finding is attributed to the inhomogeneous distribution of the negative ions (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)