Boltzmann analysis of electron swarm parameters in CHF3+CF4 mixtures

The electron drift velocity, mean energy, ionization, attachment, effective ionization coefficient, limit electricalfield, and synergism of pure CHF3 (fluoroform), pure CF4 (tetrafluoromethane), and CHF3+CF4 gas mixtures arecalculated by Boltzmann equation analysis in a wide range of density normalized electrical fields (E/N). The finitedifference method is used to solve the two-term approximation of the Boltzmann equation under steady-state Townsend conditions. To our knowledge, no previous electron swarm parameters of these mixtures have been published. At constant E/N values, the electron mean energies and drift velocities increase with decreasing CHF3 content. The addition of CF4 into the mixture increases the attachment coefficient but reduces the ionization coefficient since CF4 is more electronegative than CHF3. Furthermore, the limit electrical fields increase with increasing CF4 concentration.

PDF

___

[1] Reinking GF, Christophorou LG, Hunter SR. Studies of total ionization in gases/mixtures of interest to pulsed power applications. J Phys D Appl Phys 1986; 60: 499-508.
[2] Bradley JDB, Ay F, Wörhoff K, Pollnau M. Fabrication of low-loss channel waveguides in Al2O3 and Y2O3 layers by inductively coupled plasma reactive ion etching. Appl Phys B 2007; 89: 311–318.
[3] Altunin VV, Selover TB, Ghojel JI. Thermophysical Properties of Freons, Vol. 9: Methane Series, Part 2. Boca Raton, FL, USA: CRC Press, 1987.
[4] Muhle J, Ganesan AL, Miller BR, Salameh PK, Harth CM, Greally BR, Rigby M, Porter LW, Steele LP, Trudinger CM et al. Perfluorocarbons in the global atmosphere: tetrafluoromethane, hexafluoroethane, and octafluoropropane. Atmos Chem Phys 2010; 10: 5145–5164.
[5] Intergovernmental Panel on Climate Change. Global Warming Potential Values. Geneva, Switzerland: Intergovernmental Panel on Climate Change, 2014.
[6] Christophorou LG, Olthoff JK, Rao MVVS. Electron interactions with CF4. J Phys Chem Ref Data 1996; 25: 1341-1388.
[7] Dujko S, Raspopović ZM, Petrović ZL. Monte Carlo studies of electron transport in crossed electric and magnetic fields in CF4. J Phys D Appl Phys 2005; 38: 2952-2966.
[8] Tezcan SS, Dincer MS, Bektas S, Hiziroglu HR. Boltzmann analysis of electron swarm parameters in binary CF4+Ar mixtures. IEEE T Dielectr Electr Insul 2013; 20: 98-103.
[9] Kurihara M, Petrovic ZL, Makabe T. Transport coefficients and scattering cross-sections for plasma modelling in CF4-Ar mixtures: a swarm analysis. J Phys D Appl Phys 2000; 33: 2146-2153.
[10] de Urquijo J, Basurto E, Hernandez-Avila JL. Measurement of electron drift diffusion and effective ionization coefficients in the SF6-CHF3 and SF6-CF4 gas mixtures. J Phys D Appl Phys 2003; 36: 3132-3137.
[11] Xueli L, Dengming X. Monte Carlo simulation of electron swarm parameters in the SF6/CF4 gas mixtures. Jpn J Appl Phys 2007; 46: 4A.
[12] Tezcan SS, Duzkaya H, Dincer MS, Hiziroglu HR. Assessment of electron swarm parameters and limiting electric fields in SF6+CF4+Ar gas mixtures. IEEE T Dielectr Electr Insul 2016; 23: 1996-2005.
[13] Tezcan SS, Dincer MS and Bektas S. Effective ionization coefficients, limiting electric fields, and electron energy distributions in CF3I+CF4+Ar ternary gas mixtures. Phys Plasmas 2016; 23: 073507.
[14] National Aeronautics and Space Administration. Halocarbons: Ozone Depletion And Global Warming Overview. Washington, DC, USA: NASA.
[15] Angelinoa G, Invernizzi C. Experimental investigation on the thermal stability of some new zero ODP refrigerants. Int J Refrig 2003; 26: 51–58.
[16] Christophorou LG, Olthoff JK. Electron interactions with plasma processing gases: an update for CF4, CHF3, C2F6 and C3F8. J Phys Chem Ref Data 1999; 28: 967-982.
[17] Wang Y, Christophorou LG, Olthoff JK, Verbrugge JK. Electron drift and attachment in CHF3 and its mixtures with argon. Chem Phys Lett 1999; 304: 303-308.
[18] Hernandez-Avila JL, Basurto E and de Urquijo J. Electron transport and ionization in CHF3–Ar and CHF3–N2 gas mixtures. J Phys D Appl Phys 2004; 37: 3088–3092.
[19] White RD, Robson RE, Morrison MA, Schmidt B. Is the classical two-term approximation of electron kinetic theory satisfactory for swarms and plasmas? J Phys D Appl Phys 2003; 36: 3125-3131.
[20] Dujko S, White RD, Ness KF, Petrović ZLj, Robson RE. Nonconservative electron transport in CF4 in electric and magnetic fields crossed at arbitrary angles. J Phys D Appl Phys 2006; 39: 4788-4798.
[21] Deng Y, Xiao D. Analysis of the insulation characteristics of CF3I gas mixtures with Ar, Xe, He, N2, and CO2 using Boltzmann equation method. Jpn J Appl Phys 2014; 53: 096201.
[22] Li X, Guo X, Zhao H, Jia S, Murphy AB. Prediction of the critical reduced electric field strength for carbon dioxide and its mixtures with copper vapor from Boltzmann analysis for a gas temperature range of 300 K to 4000 K at 0.4 MPa. J Appl Phys 2015; 117: 143302.
[23] Kushner M, Zhang D. An electron impact cross section set for CHF3. J Appl Phys 2000; 88: 3231-3234.
[24] Hagelaar GJM, Pitchford LC. Solving the Boltzmann equation to obtain electron transport coefficients and rate coefficients for fluid models. Plasma Sources Sci Technol 2005; 14: 722-733.
[25] Nikitovic ZD, Stojanovic VD, Booth J, Petrovic ZL. Electron transport coefficients in mixtures of CF4 and CF2 radicals. Plasma Sources Sci Technol 2009; 18: 0350008.
[26] Dengming X, Yunkun D. Determination of electron swarm parameters in pure CHF3 and CF4 by a time-resolved method. Plasma Sci Technol 2013; 15: 25-29.
[27] Lakshminarasimha CS, Lucas J, Snelson RA. Time-of-flight electron swarm studies of ionisation and attachment in gases. Proc Inst Electr Eng 1975; 122: 1162-1165.
[28] Datskos PG, Christophorou LG, Carter JG. Effective ionization coefficients, electron drift velocities and limiting breakdown fields for gas mixtures of possible interest to particle detectors. In: IEEE Conference on Electrical Insulation and Dielectric Phenomena; 20–23 Oct. 1991; Knoxville, TN, USA. New York, NY, USA: IEEE. pp. 474–481.