Measured and calculated SF{sub 6}{sup -} collision and swarm ion transport data in SF{sub 6}-Ar and SF{sub 6}-Xe mixtures

Journal Article · Tue Mar 01 00:00:00 EST 2005 · Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics

DOI:https://doi.org/10.1103/PhysRevE.71.036405· OSTI ID:20641389

Benhenni, M; Yousfi, M; Merbahi, N; Eichwald, O ^[1]; Urquijo, J de; Hinojosa, G ^[2]; Hernandez-Avila, J L ^[3]

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1. Universite Paul Sabatier, CPAT, UMR 5002 du CNRS, 118 route de Narbonne, 31062 Toulouse cedex (France)
2. Centro de Ciencias Fisicas, Universidad Nacional Autonoma de Mexico, Apartado Postal 48-3, 62251, Cuernavaca, Mor. (Mexico)
3. Universidad Autonoma Metropolitana, CBI-Energia, Av. San Pablo 180, 02200 Mexico, D.F. (Mexico)

The measurement of the mobility of SF{sub 6}{sup -} in the mixtures SF{sub 6}-Ar and SF{sub 6}-Xe is reported over the density-reduced electric field strength E/N 1-180 Td (1 Townsend=10{sup -17} V cm{sup 2}), from a time-resolved pulsed Townsend technique. Simultaneously, the mobility of SF{sub 6}{sup -} in the same binary mixtures has been calculated from a set of collision cross sections for SF{sub 6}{sup -}-Ar, SF{sub 6}{sup -}-Xe, and SF{sub 6}{sup -}-SF{sub 6} using a Monte Carlo simulation procedure for ion transport. The good agreement between measured and calculated mobilities in these gas mixtures has led us to conclude that the validation of our cross section sets is confirmed. The elastic collision cross section, a predominant process for ion energies lower than about 10 eV, was determined from a semiclassical JWKB approximation using a rigid core potential model for the ion-neutral systems under consideration. This elastic cross section was then added to several other inelastic collision cross sections found in the literature for ion conversion, electron detachment of SF{sub 6}{sup -} and charge transfer. Moreover, the calculations of the mobility and the ratios of the transverse and longitudinal diffusion coefficients to the mobility were extended into a much wider E/N range from 1 to 4000 Td. Additionally, we have also calculated the energy distribution functions and the reaction coefficients for ion conversion and electron detachment. Finally, we have shown that the range of validity for the calculation of the mobility in gas mixtures from Blanc's law is only valid for the low E/N region, where the interaction is dominated by elastic collisions and the ion distribution function remains essentially Maxwellian.

• OSTI ID: 20641389
• Journal Information: Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics, Vol. 71, Issue 3; Other Information: DOI: 10.1103/PhysRevE.71.036405; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1063-651X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ARGON
BINARY MIXTURES
CHARGE EXCHANGE
CHARGED-PARTICLE TRANSPORT
COMPUTERIZED SIMULATION
CROSS SECTIONS
DISTRIBUTION FUNCTIONS
ELECTRIC FIELDS
ELECTRON DETACHMENT
ENERGY SPECTRA
EV RANGE 01-10
ION COLLISIONS
ION MOBILITY
MOLECULAR IONS
MONTE CARLO METHOD
SEMICLASSICAL APPROXIMATION
SULFUR FLUORIDES
TIME RESOLUTION
VALIDATION
XENON