Response analysis of electron attachment rates to C₃F₈and SF₆in buffer gases

Abstract

Electron swarm methods are applied for investigating the effects of small amounts (≤ 1.5%) of a strongly electronegative sample gas in the buffer gases Ar, N 2 or CO 2 . A pulsed Townsend method, a Monte Carlo swarm method, and a solution of the Boltzmann equation are used to determine the effective ionization rate constants of the gas mixtures. The sensitivity of the effective ionization rate constant to changes of the mixing ratio is evaluated. Our methods are benchmarked with the analysis of Ar-SF 6 and N 2 -SF 6 mixtures, and subsequently used for the analysis of gas mixtures containing C 3 F 8 . The results based on the recommended C 3 F 8 cross sections are shown to be inconsistent with the experimental data for N 2 -C 3 F 8 and CO 2 -C 3 F 8 mixtures.

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

“…However, since SF 6 is a powerful greenhouse gas (its global warming potential is 23 900 times higher than CO 2 ) 4 and is hard to degrade, its use has gradually been subjected to restrictions. As a result, there is increasing urgency to seek an environmentally friendly gas that can partially or wholly replace SF 6 .…”

“…To deal with this problem, research directed towards seeking substitutes for pure SF 6 has been widely carried out. Current research is mainly focused on mixtures of SF 6 with gases such as CF 4 , 5 C 3 F 8 , 6 N 2 O, 7 CF 3 I, 8 and on pure gases such as N 2 , CO 2 , and dry air.…”

“…Current research is mainly focused on mixtures of SF 6 with gases such as CF 4 , 5 C 3 F 8 , 6 N 2 O, 7 CF 3 I, 8 and on pure gases such as N 2 , CO 2 , and dry air. In recent years, CO 2 has attracted wide interest and extensive study due to its good interruption performance and its much lower global warming potential than SF 6 .…”

Partial discharges and breakdown in C3F8

“…Intense research on PFCs started in the early 80s. Thus, many contributions can be found concerning the characteristics of C 3 F 8 (and other PFCs) on the molecular level [18,19,20,21,22,23,24,25,26,27] and on the phenomenological level [16,28,29,30]. Although C 3 F 8 was proposed as replacement candidate in several contributions, it still has a high global warming potential compared to CO 2 .…”

Obtaining electron attachment cross sections by means of linear inversion of swarm parameters

“…Electron attachment to SF 6 and C 3 F 8 in terms of reaction rates was already investigated previously [19]. In this work, we measure rates for the pure buffer gases N 2 and CO 2 , as well as for mixtures with minor proportions ( 0.8%) of the sample gases SF 6 and C 3 F 8 .…”