Electron Swarm Parameters in and Gas Mixtures From Boltzmann Equation Analysis

The electron swarm parameters in c-C₄F₈/CO₂ gas mixtures, including the density-normalized effective ionization coefficient (α-η)/N and the drift velocity V_e, are calculated for the overall density-reduced electric-field strength E/N values from 150 to 600 Td (1 Td = 10^-17 V · cm²). These calculations have been performed through solving the Boltzmann equation under the two-term approximation in the condition of steady-state Townsend experiment. The c-C₄F₈ content k in the gas mixtures can be varied over the range of 0%-100 %. From the variation curve of (α-η)/N with the c-C₄F₈ mixture ratio k, the limiting field strength (E/N)_lim for each c-C₄F₈ concentration is determined for the analysis of the insulation characteristics of the c-C₄F₈/CO₂ mixture. Additionally, the global-warming potential and the liquefaction temperature of c-C₄ F₈/CO₂ gas mixtures are also taken into account to evaluate the possibility of applying in gas insulation of power equipment.