Materials Data on SF6 by Materials Project
SF6 crystallizes in the monoclinic C2/m space group. The structure is zero-dimensional and consists of six sulfur hexafluoride molecules.
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Materials Data on Cs3H(SF6)2 by Materials Project
Cs3H(SF6)2 crystallizes in the orthorhombic Pba2 space group. The structure is three-dimensional. there are two inequivalent Cs1+ sites. In the first Cs1+ site, Cs1+ is bonded in a 8-coordinate geometry to two equivalent H1+ and fourteen F1- atoms. There are one shorter (3.24 Å) and one longer (3.42 Å) Cs–H bond lengths. There are a spread of Cs–F bond distances ranging from 3.19–3.65 Å. In the second Cs1+ site, Cs1+ is bonded in a 12-coordinate geometry to twelve F1- atoms. There are a spread of Cs–F bond distances ranging from 3.05–3.61 Å. H1+ is bonded in a linear geometry to two equivalent Cs1+ and two equivalent F1- atoms. Both H–F bond lengths are 1.14 Å. S4+ is bonded in a square pyramidal geometry to five F1- atoms. There are a spread of S–F bond distances ranging from 1.63–1.80 Å. There are six inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to four Cs1+ and one H1+ atom. In the second F1- site, F1- is bonded in a distorted single-bond geometry to three Cs1+ and one S4+ atom. In the third F1- site, F1- is bonded in a distorted single-bond geometry to three Cs1+ and one S4+ atom. In the fourth F1- site, F1- is bonded in a distorted single-bond geometry to three Cs1+ and one S4+ atom. In the fifth F1- site, F1- is bonded in a distorted single-bond geometry to three Cs1+ and one S4+ atom. In the sixth F1- site, F1- is bonded in a single-bond geometry to three Cs1+ and one S4+ atom.
36 MATERIALS SCIENCE↗
Absolute elastic differential electron scattering cross sections in the intermediate energy region. III - SF6 and UF6
A recently developed technique has been used to measure the ratios of elastic differential electron scattering cross sections (DCS) for SF6 and UF6 to those of He at electron impact energies of 5, 10, 15, 20, 30, 40, 50, 60, and 75 eV and at scattering angles of 20 to 135 deg. In order to obtain the absolute values of DCS from these ratios, He DCS of McConkey and Preston have been employed in the 20 to 90 deg range. At angles in the 90 to 135 deg range the recently determined cross sections of Srivastava and Trajmar have been utilized. From these DCS, elastic integral and momentum transfer cross sections have been obtained.
Srivastava, S. K.↗
Electron impact excitation of SF6
A study of the electron impact energy-loss spectrum of SF6 under both optical (low scattering angle, high impact energy) and non-optical conditions (high scattering angle, low impact energy) has revealed a number of electronic excitation processes. With the help of theoretical calculations, several of these transitions have been assigned and approximate cross sections associated with four features have been determined. In addition, a strong resonance at 12 eV has been observed in both elastic and vibrationally inelastic (delta E = 0.092 eV) channels.
Trajmar, S.↗
Collisionless dissociation of SF6 using two resonant frequency CO2 laser fields
The collisionless dissociation of SF6 has been studied using simultaneous irradiation by two frequencies from a CO2 laser which are both nearly resonant with the SF6nu3 absorption band. It was found that the dissociation was enhanced, and occurred over a wider frequency range, than for single frequency dissociation. No threshold effect was observed for a weak resonant and a much higher energy field pumping slightly off-resonance. For such two frequency irradiation, the peak in the dissociation curve was found to be shifted to lower frequencies with respect to that for single frequency dissociation.
Gower, M. C.↗
Experimental SF6/-//SF6 and Cl/-//CFC13 electron-attachment cross sections in the energy range 0-200 meV
Experimental cross sections for the electron-attachment processes for SF6(-)/SF6 and Cl(-)/CFl3 are reported in the energy range 0-200 meV by normalizing each attachment line shape to measurement of a thermal rate coefficient. When the same ion states are detected, good agreement is found between present values, for which a monoenergetic electron source is used, and swarm-unfolded results. The present data constitute a new limit for cross sections reported at high resolution at the lowest electron energy.
Chutjian, A.↗
Calculation of SF6-/SF6 and Cl-/CFCl3 electron attachment cross sections in the energy range 0-100 meV
Electron attachment cross sections for the processes SF6-/SF6 and Cl-/CFCl3 are calculated in a local theory using a model in which diatomic-like potential energy curves for the normal modes are constructed from available spectroscopic data. Thermally populated vibrational and rotational levels are included. Good agreement is found with experimental cross sections in the energy range 5-100 meV for a particular choice of potential energy curve parameters.
Chutjian, A.↗
Effects on H(-) production in a multicusp ion source by mixture of H2 with H2O, NH3, CH4, N2H4, and SF6
Effects of H(-) production in a multicusp ion source are measured by separately mixing with hydrogen small amounts (0.33-10 percent) of water, ammonia, methane, and hydrazine these are molecules which produce large amounts of H(-) via dissociative attachment (DA) resonances at higher electron energies. The mixing was done in a separate reservoir, with careful measurement of individual pressures. Experimental enhancements of 1.4 and less were observed, whereas calculated enhancements, using accurate DA cross sections for ground-state H2, should have produced factors of 1.5, 3.0, 1.3, and 2.4 enhancements for water, ammonia methane, and hydrazine, respectively, at a mean electron energy of 1.0 eV in the extraction region. The difference is accounted for by including, in the enhancement calculation, vibrationally and rotationally excited H2 molecules, with v-double prime = 5-11, and J-double prime = 0-5, and the large DA cross sections for the excited H2 (v-double prime, J-double prime). The relative populations of H2 (v-double prime, J-double prime) thus obtained are found to be substantially smaller than those predicted by theoretical calculations. The effect on H(-) current was also studied by mixing small amounts of SF6 with H2. A 1.5 percent mixture was found to reduce the H(-) output by one half.
Orient, O. J.↗
Infrared spectroscopic measurements of the vertical column abundance of sulfur hexafluoride, SF6, from the ground
The solar observations involved in the present monitoring evaluation were made at two facilities, using Fourier-transform spectrometers achieving spectral resolutions of 0.005/cm and signal-to-rms noise ratios for individual scans from near 500 to near 1000. The monthly mean total vertical-column abundances of SF6 above both facilities are reported for time intervals from June 1986 to June 1990 and from March 1981 to June 1990. It is found that the vertical-column abundances increased at mean rates of 6.9 +/- 2.8 pct above one station and 6.6 +/- 7.2 pct above the other. Since all the results were retrieved using the same spectroscopic parameters and similar nonlinear least-squares curve-fitting algorithms validated through intercomparison exercises, the large error reported for the second station is attributed to a larger measurement uncertainty due to stronger H2O and C2O interferences, and a greater variability during each month.
Zander, R.↗
A numerical study of Li-SF6 wick combustion - Forced and mixed convective burning
A numerical study is conducted to study Li-SF6 wick diffusion flames under mixed convective burning conditions at a pressure of 0.01 MPa. Both planar and cylindrical wicks are considered. The model is based on a conserved scalar approach. The objective of this study is to assess the effects of particular parameters on the burning rate and heat transfer. The flat-plate solution yields a fuel mass burning rate per unit surface area following the x exp -1/2 dependence of the classical similarity solution, where x is the streamwise distance. Cylindrical wick geometries yield enhanced burning rates over planar wicks. For the case of mixed convective burning, the burning rate results approach either the forced or natural convective burning limits as ambient streamwise velocity is changed. Critical Richardson numbers specifying these burning limits are determined for a given condition. Reducing gravity results in a lower burning rate because the influence of natural convection is diminished. Under reduced gravity of 1/1000 of the sea-level value, mixed convective burning nearly resembles forced convection.
Damaso, R. C.↗
Infrared absorption-coefficient data on SF6 applicable to atmospheric remote sensing
Spectral absorption coefficients, k(nu)/cm per atm, of SF6 have been measured in the central Q-branches of the nu(3)-fundamental at 947/cm at various temperature-pressure combinations representing tangent heights in solar-occultation experiments or layers in the atmosphere. The data obtained with the Doppler-limited spectral resolution (about 0.0001/cm) of a tunable-diode laser spectrometer are useful in the atmospheric remote sensing of this trace gas.
Varanasi, P.↗
Infrared Imaging Of Flows Seeded With SF6
Novel technique enables repeated measurements of flow patterns during flight. Wing-tip vorticity studied in flight by observing infrared emissions from SF6 gas entrained in wing-tip flow. System makes vortical flows visible throughout all altitude and speed ranges of all subsonic aircraft. Also useful for transonic and supersonic speeds. Primary application is testing of aircraft in flight, also proves useful in testing fast land vehicles and structures or devices subject to strong winds.
Manuel, Gregory S.↗
Infrared spectroscopic parameters of COF2, SF6, ClO, N2, and O2
The status of the middle infrared spectroscopy of selected atmospheric trace gases, COF2, SF6, ClO, N2, and O2 is reviewed. Emphasis is placed on improved sets of spectroscopic parameters that have been included in the 1991 and 1992 versions of the HITRAN database.
Rinsland, Curtis P.↗
Spectral absorption-coefficient data on HCFC-22 and SF6 for remote-sensing applications
Spectral absorption-coefficients (cross-sections) kappa(sub nu) (/cm/atm) have been measured in the 7.62, 8.97, and 12.3 micrometer bands of HCFC-22 (CHClF2) and the 10.6 micrometer bands of SF6 employing a high-resolution Fourier-transform spectrometer. Temperature and total pressure have been varied to simulate conditions corresponding to tropospheric and stratospheric layers in the atmosphere. The kappa(sub nu) are compared with values measured by us previously using a tunable diode laser spectrometer and with the appropriate entries in HITRAN and GEISA, two of the databases known to the atmospheric scientist. The measured absolute intensities of the bands are compared with previously published values.
Varanasi, P.↗
BOREAS TGB-1 NSA SF6 Chamber Flux Data
The BOREAS TGB-1 team made several chamber and tower measurements of trace gases at sites in the BOREAS NSA. This data set contains sulfur hexafluoride (SF6) dark chamber flux measurements at the NSA-OJP and NSA-YJP sites from 16-May through 13-Sep-1994. Gas samples were extracted approximately every 7 days from dark chambers and analyzed at the NSA lab facility. The data are provided in tabular ASCII files.
Crill, Patrick↗
Satellite Boreal Measurements over Alaska and Canada During June-July 2004: Simultaneous Measurements of Upper Tropospheric CO, C2H6, HCN, CH3Cl, CH4, C2H2, CH2OH, HCOOH, OCS, and SF6 Mixing Ratios
Simultaneous ACE (Atmospheric Chemistry Experiment) upper tropospheric CO, C2H6, HCN, CH3Cl, CH4 , C2H2 , CH30H, HCOOH, and OCS measurements show plumes up to 185 ppbv (10 (exp -9) per unit volume) for CO, 1.36 ppbv for C2H6, 755 pptv (10(exp -12) per unit volume) for HCN, 1.12 ppbv for CH3C1, 1.82 ppmv, (10(exp -6) per unit volume) for CH4, 0.178 ppbv for C2H2, 3.89 ppbv for CH30H, 0.843 ppbv for HCOOH, and 0.48 ppbv for OCS in western Canada and Alaska at 50 deg N-68 deg N latitude between 29 June and 23 July 2004. Enhancement ratios and emission factors for HCOOH, CH30H, HCN, C2H6, and OCS relative to CO at 250-350 hPa are inferred from measurements of young plumes compared with lower mixing ratios assumed to represent background conditions based on a CO emission factor derived from boreal measurements. Results are generally consistent with the limited data reported for various vegetative types and emission phases measured in extratropical forests including boreal forests. The low correlation between fire product emission mixing ratios and the S176 mixing ratio is consistent with no significant SF6 emissions from the biomass fires.
Rinsland, Curtis P.↗
Industry Scan of Non-SF6 Gas-Insulated Technologies
Sulfur Hexafluoride (SF 6 ) is a specialty gas with excellent electrical insulation properties which has been used extensively in the power industry. This gas is unfortunately also one of the most potent greenhouse gases known to humanity. A 2014 report by the Intergovernmental Panel on Climate Change found that SF 6 has a global warming potential (GWP) 23,000 times higher than Carbon Dioxide, and has the highest GWP of all gases assessed (Myhre 2013). SF 6 is almost exclusively man-made and is produced for use as an insulator in high voltage electrical equipment. This makes the production and use of SF 6 one of the leading sources of anthropogenic climate change. Since SF 6 recognition as a significant contributor to climate change, most governments and organizations have sought ways to reduce or eliminate their use of this gas. Many utilities have initiated leak monitoring and repair programs which have significantly reduced emissions of this gas into the atmosphere. While leak reduction programs have been effective at reducing emission rates in the developed world, leak rates remain frozen at ~1% annually. However, one of the largest and fastest growing markets for this gas is in the developing world where emissions standards are often lacking (P&S Intelligence. 2023). To fully eliminate the environmental impacts of SF 6 , alternative technology is needed. The ideal replacement would be a technology that can fulfil the same role as SF 6 , at the same cost or cheaper, but without adverse environmental effects. Currently, no technology fits this description, however several promising technologies have begun to enter the market. This report was commissioned by the United States Department of Energy’s Office of Electricity under the Transformer Resilience and Advanced Components (TRAC) program to assess the state of industry adoption and manufacturing capability for SF 6 -free alternative technologies for use at the high-voltage level, and the primary barriers to broader adoption. While this report is tailored to the United States, the findings should be relevant to all stakeholders seeking to reduce SF 6 emissions.
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Materials Data on Ge(SF6)2 by Materials Project
GeF6(SF3)2 crystallizes in the orthorhombic Pnnm space group. The structure is zero-dimensional and consists of two GeF6 clusters and four SF3 clusters. In each GeF6 cluster, Ge4+ is bonded in an octahedral geometry to six F1- atoms. There is two shorter (1.83 Å) and four longer (1.84 Å) Ge–F bond length. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one Ge4+ atom. In the second F1- site, F1- is bonded in a single-bond geometry to one Ge4+ atom. In each SF3 cluster, S4+ is bonded in a 3-coordinate geometry to three F1- atoms. There is one shorter (1.56 Å) and two longer (1.57 Å) S–F bond length. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one S4+ atom. In the second F1- site, F1- is bonded in a single-bond geometry to one S4+ atom.
36 MATERIALS SCIENCE↗