Vol.2, No 5, 2003 pp. 285 - 291
UDC 533.92
SOME TRANSPORT PROPERTIES IN PLASMAS
CONTAINING ARGON AND FLUORINE
R N. V. Novaković1, B. S. Milić2,
S. M. Stojilković3, D. Ž. Gajić1
1Faculty of Sciences and Mathematics,
Niš, Serbia
2Faculty of Physics, University of
Belgrade, P.O.Box 368, 11001 Belgrade, Serbia
3Faculty of Electronics, University
of Niš, P.O.Box 73, 18001 Niš, Serbia
Abstract. In this paper some results of numerical evaluation of
transport coefficients in plasmas in the mixtures of argon and fluorine
are presented. These transport characteristics are given in the function
of the temperature for low pressures ranging from 0,1 kPa to 1,0 kPa and
for low temperatures between 500 K and 5 000 K in argon plasmas with 20%
and 30% of the fluorine added. It is assumed that the system is kept under
constant pressure and that a corresponding state of local thermodynamical
equilibrium (LTE) is attained in it. The equilibrium plasma composition,
necessary for the evaluations, was determined on the ground of the Saha
equations for ionization processes and the law of mass action for the thermal
dissociation of F2, combined with the charge
conservation relation and the assumption that the pressure remained constant
in the course of temperature variations. The ionization energy lowering,
required in conjunction with the Saha equations, was obtained with the
aid of a modified expression for the plasma Debye radius proposed previously.
A previously derived expression for the modified Debye radius, offering
the possibility to treat the plasmas considered as weakly non-ideal in
the whole temperature range, is used. The cut-off at the Landau length
rather than of the smallest of ionic radii is introduced. This alteration
in the evaluation procedure brings different considerable changes in the
final numerical results for the all relevant quantities.
Key words: argon, fluorine, weakly non-ideal plasma, number
density, electron and ion diffusion coefficients, electrical conductivity,
thermal conductivity, collision frequency.
NEKE TRANSPORTNE OSOBINE
U PLAZMI ARGONA I FLUORA
Dati su neki rezultati numeričkog izračunavanja transportnih koeficijenata
u plazmi smeše argona i fluora. Ove transportne karakteristike su date
u funkciji temperature za niske pritiske (od 0,1 kPa do 1,0 kPa) i za niske
temperature (od 500 K do 5 000 K) u argonovoj plazmi sa dodatkom 20 % i
30% fluora. Uzeto je da je sistem na konstantnom pritisku u stanju lokalne
termodinamičke ravnoteže. Korišćen je modifikovani izraz za Debye-ev radijus,
što je omogućilo da posmatrana plazma bude tretirana kao slabo neidealna
u celom temperaturnom intervalu. Uzeta je Landau-ova dužina u izrazu za
modifikovan Debye-ev radijus umesto manjeg jonskog radijusa. Ovakav izbor
pri izračunavanju daje različite promene u konačne numeričke rezultate.
