Collisional decomposition of the sulfur hexaflouride anion (SF6−)

Abstract

Insulating gas mixtures containing SF6 have been promoted to serve as replacements for pure SF6 in order to reduce SF6 atmospheric emission. It has been argued that some synergism may be achieved by choosing proper buffer gases in mixtures with SF6 such that the buffer gases efficiently slow down electrons into an energy range where the electron attachment cross section for SF6 is large. A complete understanding of the dielectric properties of SF6 mixtures obviously requires information about electron detachment from SF6" as collisional electron detachment may be the principal source of discharge initiation in SF6 mixtures. In this paper, we report total cross-section measurements for electron detachment and collision induced dissociation for collisions of SF6"with N2 for collision energies ranging up to a few hundred eV. The experimental results are analyzed using a two-step collision model where the unimolecular decomposition of collision ally excited SF6" ions is described in a statistical framework.

Relationship between PD magnitude distribution and pulse burst for positive coronas

“…In this case, both the concentration of negative ions and the electric field near the tip gradually increased due to the movement of ions. The increases of negative ions concentration and electric field enhanced the collisional and field-induced detachments of negative ions [18,19]. In a short duration, numerous primary electrons from detachments can trigger several discharges.…”

Thermochemistry of the Reaction of SF6 with Gas-Phase Hydrated Electrons: A Benchmark for Nanocalorimetry

“…Because of its high electron affinity, low toxicity, and chemical stability, SF 6 finds a wide range of technological applications, for example, as an electron scavenger in electrical switching devices and plasma reactors and in the electrical power industry as an insulator for gas-insulated equipment in power stations. − On the contrary, sulfur hexafluoride is also considered to be a very potent greenhouse gas. It has a very long residence lifetime, and it is inert to chemical or photolytic degradation. − The concentration of the efficient infrared absorber in the atmosphere has increased in recent years .…”

Electron attachment to SF6under well defined conditions: comparison of statistical modeling results to experiments

“…Champion et al 26 have shown that at higher energies dissociation becomes significant, as indicated by the relative k(E,J) curves for detachment and dissociation. Thermal detachment has been mainly ignored previously although it was looked for at temperatures below 600 K and not observed (see Christophorou and Olthoff 4 and Spangl et al 20 ) In order to determine thermal detachment rates, the SF 6 7SF 5 ' ratio at fixed temperature, pressure, electron concentration, and SF 6 concentration was measured as a function of residence time in the FALP apparatus.…”