Electron detachment from negative ions in sulphur hexafluoride

Abstract

A novel method for the investigation of electron detachment from negative ions has been developed. It allows the study of the influence of the age of the ions on the detachment process. Measurements were performed on sulphur hexafluoride at 73.3 and 110 mbar. The reduced detachment coefficient delta /n was obtained for a narrow range of E/n values around 3.8*10-15 V cm2. A significant influence of the age of the ions on delta /n was found, which is interpreted as being due to excited states of SF6-.

Integrated effect on evolution of streamer dynamics under long-term repetitive sub-microsecond pulses in high-pressure nitrogen

“…Under a low-amplitude DC sweeping voltage, free electrons are expected to be swept away or absorbed due to their high mobility. The electron detachment process from negative ions is dependent on the ion energy [74], which mainly happens under the high amplitude voltage pulse rather than the low amplitude DC sweeping voltage. Therefore, the seed electron source produced by the detachment from negative ions may still play an important role for the initiation and propagation of subsequent positive streamers.…”

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.…”

Electron Attachment and Detachment Processes in Electronegative Gases

“…27 where the thermal rate constant for associa- and close to the orbitingLangevin collision rate constant, kerb = 27~e(or/J1,)~~~ (a is the polarizability of the target species, and M , is the reduced mass of the collision pair). Finally, there has been some work [154, 1551 on electron detachment in SF, at densities in the range 0.8 to 615 x lo1' molecules [154] and a t 18 and 27 x 101' molecules ~r n -~ [155] and a t EIN 350 x lo-'' V cm2. The uncertainty in the identity of the negative ions formed in these experiments obscured proper interpretation of the measurements.…”

“…The electron detachment coefficient was found to decrease with SF, gas density (see Pig. 28), and this was attributed [155] to a three-body detachment process involving (SF6-) SF, clusters; the electron was presumed to be more tightly bound in such cluster anions compared with SF,-. Clearly, more work is needed in this area.…”