Plasma chemical model for decomposition of SF6 in a negative glow corona discharge

A zonal plasma chemical model is proposed to account for the observed oxidation and decomposition of sulfur hexafluoride (SF6) by a negative, point-to-plane glow-type corona discharge in pressurized SF6/O2/H2O gas mixtures. The model yields dependencies of stable neutral oxidation by-products such as SOF2, SO2F2, SOF4, S2F10, and SO2 on time, discharge current, and O2 and H2O concentrations which are consistent with measured results. Electron-impact-induced dissociation of SF6 in the glow region of the discharge is the decomposition rate-controlling process. The relative roles played by different reactions involving neutral free radicals and ions in different zones of the discharge are examined, and in some cases, reaction rate coefficients have been adjusted within reasonable limits to give best fits to observed production rates of various by-products. Problems of uniqueness that arise because of gaps in our knowledge about important processes that should be included in the model are also discussed.

[1]  J. Moruzzi,et al.  Attachment, detachment and ion-molecule reactions in SO2 and SO2-O2 mixtures , 1981 .

[2]  G. Streit,et al.  Negative ion–molecule reactions of SF4 , 1981 .

[3]  I. Sauers,et al.  Detection of S2F10 produced by a single‐spark discharge in SF6 , 1993 .

[4]  A. MacDiarmid,et al.  Formation of Pentafluorosulfur Fluorosulfonate and Bispentafluorosulfur Oxide from the Direct Reaction of the Elements , 1962 .

[5]  H. F. Winters,et al.  Total dissociation cross section of CF/sub 4/ and other fluoroalkanes for electron impact , 1982 .

[6]  B. Stevens,et al.  Progress in reaction kinetics , 1961 .

[7]  R. J. Brunt,et al.  Rate constants for fluoride transfer from sulfur hexafluoride(1-) to fluorinated gases and sulfur dioxide: temperature dependence and implications for electrical discharges in sulfur hexafluoride , 1988 .

[8]  J. Coulon,et al.  Mass spectrometric detection of S2F and S2F2 in SF6-18O2 RF discharges , 1991 .

[9]  D. Mcdaniel,et al.  Fluoride ion affinity of some Lewis acids , 1973 .

[10]  D. Kahaner,et al.  Acuchem: A computer program for modeling complex chemical reaction systems , 1988 .

[11]  Wing Tsang,et al.  Chemical Kinetic Data Base for Combustion Chemistry. Part I. Methane and Related Compounds , 1986 .

[12]  L. G. Christophorou,et al.  Neutral Decomposition Products in Spark Breakdown of SF6 , 1986, IEEE Transactions on Electrical Insulation.

[13]  L. Christophorou,et al.  Low energy electron attachment to SF6 in N2, Ar, and Xe buffer gases , 1989 .

[14]  J. Lyman,et al.  CO2 laser induced reactions of SF5Cl , 1978 .

[15]  Permanent Dissociation of Sulphur Hexa-fluoride in Corona Discharges , 1955, Nature.

[16]  L. G. Christophorou,et al.  Gaseous Dielectrics III , 1982 .

[17]  Chutjian,et al.  s-wave threshold in electron attachment: Observations and cross sections in CCl4 and SF6 at ultralow electron energies. , 1985, Physical review. A, General physics.

[18]  R. J. Brunt,et al.  Role of photodetachment in initiation of electric discharges in SF6 and O2 , 1983 .

[19]  R. J. Vanbrunt,et al.  Production Rates for Oxyfluorides SOF2, SO2F2, and SOF4 in SF6 Corona Discharges. , 1985, Journal of research of the National Bureau of Standards.

[20]  L. Christophorou,et al.  Gas phase hydrolysis of sulfur tetrafluoride: A comparison of the gaseous and liquid phase rate constants , 1985 .

[21]  A. Belarbi,et al.  Optical detection of corona discharges in SF6, CF4, and SO2 under dc and 50-Hz ac voltages , 1991 .

[22]  L. K. Fifield,et al.  Aspects of breakdown product contamination of sulphur hexafluoride in electrostatic accelerators , 1983 .

[23]  N. Wiegart,et al.  The mechanism of leader breakdown in electronegative gases , 1989 .

[24]  T. Mcmahon,et al.  Fluoride and chloride affinities of main group oxides, fluorides, oxofluorides, and alkyls. Quantitative scales of Lewis acidities from ion cyclotron resonance halide-exchange equilibria , 1985 .

[25]  K. R. Ryan.  Aspects of the chemistry of SF6/O2 plasmas , 1989 .

[26]  I. C. Plumb,et al.  Gas-phase reactions in plasmas of SF6 with O2 in He , 1988 .

[27]  Yoshiharu Nakamura.  Transport coefficients of electrons and negative ions in SF6 , 1988 .

[28]  R. Grob,et al.  Study of the decomposition of wet SF6, subjected to 50‐Hz ac corona discharges , 1989 .

[29]  J. Fendler,et al.  CONDUCTOMETRIC PULSE RADIOLYSIS OF SULFUR HEXAFLUORIDE IN AQUEOUS SOLUTIONS. RATE OF HYDROLYSIS OF SULFUR TETRAFLUORIDE. , 1970 .

[30]  D. K. Davies,et al.  Dielectric properties for SF6 and SF6 mixtures predicted from basic data , 1979 .

[31]  John Crank,et al.  The Mathematics Of Diffusion , 1956 .

[32]  I. C. Plumb,et al.  A model for the etching of silicon in SF6/O2 plasmas , 1990 .

[33]  A. Mccoubrey.  The Band Fluorescence of Mercury Vapor , 1954 .

[34]  R. J. Van Brunt,et al.  Electron‐transport, ionization, attachment, and dissociation coefficients in SF6 and its mixtures , 1988 .

[35]  F. Kneubühl,et al.  Mass spectrometry of arcs in SF6 circuit breakers , 1985 .

[36]  R. J. Van Brunt,et al.  Fundamental processes of SF/sub 6/ decomposition and oxidation in glow and corona discharges , 1990 .

[37]  I. C. Plumb,et al.  Gas-phase reactions of SF5, SF2, and SOF with O(3P): Their significance in plasma processing , 1986 .

[38]  I. Sauers,et al.  A mass spectrometric study of positive and negative ion formation in an SF6 corona. II. Influence of water and SF6 neutral by-products , 1992 .

[39]  L. W. Sieck.  Thermochemistry of solvation of sulfur hexafluoride monoanion by simple polar organic molecules in the vapor phase , 1986 .

[40]  L. Kline,et al.  Electron and Chemical Kinetics in the Low-Pressure RF Discharge Etching of Silicon in SF6 , 1986, IEEE Transactions on Plasma Science.

[41]  R. J. Brunt,et al.  Identification of corona discharge-induced SF6 oxidation mechanisms using SF6/18O2/H216O and SF6/16O2/H218O gas mixtures , 1988 .

[42]  G. Gutsev,et al.  A theoretical investigation on the molecular and electronic structure of the SFn compounds n=1-5 and their singly charged negative ions , 1992 .

[43]  J. Czarnowski,et al.  The kinetics and the mechanism of the thermal decomposition of bis‐pentafluorosulfurtrioxide (SF5OOOSF5) , 1979 .

[44]  G. T. Kohman,et al.  Electrical Decomposition of Sulfur Hexafluoride , 1953 .

[45]  P. J. Chantry,et al.  A simple formula for diffusion calculations involving wall reflection and low density , 1987 .

[46]  G. Woolsey,et al.  Diffuse and constricted glow discharges in SF6 , 1987 .

[47]  S. Benson.  Molecular models for recombination and disproportionation of radicals , 1983 .

[48]  J. Herron.  S2 F10 Formation in Computer Simulation Studies of the Breakdown of SF6 , 1987, IEEE Transactions on Electrical Insulation.

[49]  P. L. Patterson.  Mobilities of Negative Ions in SF6 , 1970 .

[50]  R. J. Brunt,et al.  Collisional electron detachment and decomposition rates of SF−6, SF−5, and F− in SF6: Implications for ion transport and electrical discharges , 1989 .

[51]  Isidor Sauers,et al.  By-product formation in spark breakdown of SF6/O2 mixtures , 1988 .

[52]  R. J. Van Brunt,et al.  Gas‐phase hydrolysis of SOF2 and SOF4 , 1986 .

[53]  K. Becker,et al.  Absolute cross sections for fluorine 3p→3s line emissions following single electron impact on NF3, CF4, and SF6 , 1987 .

[54]  A. Belarbi,et al.  Study of the decomposition of SF6 under dc negative polarity corona discharges (point‐to‐plane geometry): Influence of the metal constituting the plane electrode , 1992 .

[55]  R. J. Brunt,et al.  Electron-energy dependence of the S2F10 mass spectrum , 1989 .

[56]  Richard J. Van Brunt,et al.  Characterization of point‐plane corona pulses in SF6 , 1981 .

[57]  W. Tsang,et al.  Kinetics and thermodynamics of the reaction SF6⇄SF5+F , 1992 .

[58]  A. Phelps,et al.  THEORY OF ELECTRON COLLISION EXPERIMENTS AT INTERMEDIATE AND HIGH GAS DENSITIES. Technical report No. 32 , 1966 .

[59]  R. J. Brunt,et al.  Transfer of F− in the reaction of SF6− with SOF4: Implications for SOF4 production in corona discharges , 1988 .

[60]  I. Sauers,et al.  A mass spectrometric study of positive and negative ion formation in an SF6 corona. I. Sources of sulphur-fluoride ions , 1992 .

[61]  G. Streit.  Negative ion chemistry and the electron affinity of SF6 , 1982 .

[62]  R. Zare,et al.  Stepwise bond dissociation energies in sulfur hexafluoride , 1980 .

[63]  G. Gutsev,et al.  The structure and stability of S2F10 and S2F11 and their anions , 1991 .

[64]  R. J. Brunt,et al.  Detection of trace disulfur decafluoride in sulfur hexafluoride by gas chromatography/mass spectrometry , 1991 .

[65]  I. C. Plumb,et al.  Gas-phase combination reactions of SF4 and SF5 with F in plasmas of SF6 , 1988 .

[66]  W. Schmidt,et al.  Electron detachment from negative ions of sulphur hexafluoride-swarm experiments , 1991 .

[67]  R. Grob,et al.  Study of the decomposition of SF/sub 6/ in the presence of water, subjected to gamma irradiation or corona discharges , 1988 .

[68]  R. A. Cox,et al.  Evaluated kinetic and photochemical data for atmospheric chemistry: Supplement II , 1989 .

[69]  L. Christophorou.  Electron Attachment and Detachment Processes in Electronegative Gases , 1987 .

[70]  Morrow.  Properties of streamers and streamer channels in SF6. , 1987, Physical review. A, General physics.

[71]  I. Sauers.  Sensitive Detection of By-Products Formed in Electrically Discharged Sulfur Hexafluoride , 1986, IEEE Transactions on Electrical Insulation.

[72]  J. Herron.  A critical review of the chemical kinetics of SF4, SF5, and S2F10 in the gas phase , 1987 .

[73]  H. Mukae,et al.  Diagnostic Technique of Gas Insulated Substation by Partial Discharge Detection , 1980, IEEE Transactions on Power Apparatus and Systems.