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Space Potential and Ion Energies in a Low Pressure Discharge Containing at least Two Negative Species

Published online by Cambridge University Press:  22 February 2011

S G Ingram  and
N St J Braithwaite
S G Ingram
Affiliation:
Department of Engineering Science, Parka Road, Ozford, OX1 3PJ, U.K.
N St J Braithwaite
Affiliation:
Materials Discipline, Faculty of Technology, The Open University, Walton Hall, Milton Keynes, MK7 6AA, U.K
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Abstract

A Tonks-Langmuir type model for a one-dimensional low pressure (collisionless) plasma containing at least two species of Maxwellian negative charge carriers is examined. The solutions of this model yield the positive ion energy distribution at the sheath edge without needing to specify the ionization process. This distribution has a width consistent with the potential drop across the plasma, and is shown to satisfy the generalised Bohm criterion for sheath formation. However by assuming a form for the ionization rate in the plasma, the potential profile across the discharge has been calculated. It has been found that for a range of plasma parameters the solution for the potential at which quasineutrality fails becomes triple valued; the physical solution in this regime is identified.

Many plasmas used for materials processing contain negative ions. It is important to understand how these ions influence the positive ion energy distribution at the substrate where the processing occurs.

This work is also of relevance to the behaviour of Langmuir probes in electronegative plasmas.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 117: Symposium C – Process Diagnostics: Materials, Combustion, Fusion , 1988 , 281
Copyright
Copyright © Materials Research Society 1988

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References

1. Chapman, B ‘Glow discharge processes’ John Wiley and sons 1980, N M P Benjamin et al these proceedingsGoogle Scholar
2. Thompson, B E et al (1986) J Appl Phys 59, 1890 CrossRefGoogle Scholar
3. Ingram, S G and Braithwaite, N St J (1988) submitted to J Phys DGoogle Scholar
4. Bohm, D ‘The characteristics of electrical discharges in magnetic fields’ McGraw-Hill 1949 Google Scholar
5. Tonks, L and Langmuir, I (1929) Phys Rev 34, 876 CrossRefGoogle Scholar
6. Self, S A (1963) Phys fluids 6, 1762 CrossRefGoogle Scholar
7. Emmert, G A et al (1980) Phys Fluids 23, 803 CrossRefGoogle Scholar
8. Harrison, E R and Thompson, W B (1959) Proc Phys Soc 74, 145, Caruso, A and Cavaliere, A (1962) Il Nuovo Cimento 26, 1389 9. B Bezzerides et al (1978) Phys Fluids 21, 2179CrossRefGoogle Scholar
10. Braithwaite, N St J and Allen, J E (1986) OUEL report 1636/86 Department of Engineering Science. Oxford University U.K.Google Scholar
11. Schott, L (1987) Phys fluids 30, 1795 CrossRefGoogle Scholar
12. Wickens, L M D. Phil Thesis (1980) OxfordGoogle Scholar
13. Woolsey, G A et al (1967) Int J Electron 22, 235 CrossRefGoogle Scholar