Response analysis of electron attachment rates to C3F8 and SF6 in buffer gases

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 CO2. 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-SF6 and N-2-SF6 mixtures, and subsequently used for the analysis of gas mixtures containing C3F8. The results based on the recommended C3F8 cross sections are shown to be inconsistent with the experimental data for N-2-C3F8 and CO2-C3F8 mixtures.