Factors of the Synergy Effect of Insulating Gas Mixtures
Abstract
The critical values of the reduced electric field (E/N)_lim of SF_6/N2 are higher than the partial pressure weighted values given by linear interpolation between those of pure SF6 and N_2. Furthermore, (E/N)_lim of SF_6/C_4F8 partly exceeds even that of SF_6. These properties are called synergy effect. We have analyzed the synergy effect from a viewpoint of collaboration between electron collision and attachment, and the following characteristics of SF_6, C_4F8 and N2 have been indicated as primary factors of the synergy effect: (a) a large attachment cross section of SF6 laying in a low electron energy region, (b) a steep rise at the onset energy of an electronic excitation cross section of C_4F_8, and (c) the presence of the peaks of the elastic collision and vibrational excitation cross sections of N_2. Factor (a) plays the primary role for electron capture, and it is assisted by factors (b) and (c) in SF_6/C_4F8 and in SF_6/N_2, respectively. Factor (b) feeds electrons into the low-energy region in which factor (a) works efficiently. Factor (c) impedes the energy gain of low-energy electrons and prolongs the electron residence time in the low-energy region, that promotes the electron attachment. We will discuss electron behavior in SF_6/C_4F_8, SF_6/N2 and model gases, focusing on the factors.
- Publication:
-
APS Annual Gaseous Electronics Meeting Abstracts
- Pub Date:
- October 2003
- Bibcode:
- 2003APS..GECGTP046I