Electron attachment and ionization processes in CF4, C2F6, C3F8, and n-C4F1

Abstract

Measurements are reported of the electron attachment (ηT/N) and ionization (αT/N) coefficients for the perfluoroalkanes n-CNF2N+2 (N=1 to 4) over the density-reduced electric field (E/N) range 5×10−17≤E/N≤400×10−17 V cm2 using pulsed Townsend (PT) experimental techniques. The present ηT/N measurements are the first to be obtained for pure C2F6, C3F8, and n-C4F10 at low E/N values. The ηT/N measurements in C3F8 and n-C4F10 are dependent on gas pressure over a wide E/N range in agreement with previous high pressure electron attachment rate constant ka measurements in these gases. The dissociative and nondissociative electron attachment processes for C3F8 and n-C4F10 have been quantified from the pressure dependence of the measured electron attachment coefficients ηT/N as a function of E/N. The thermal electron attachment rate constants (ka)th and the high voltage limiting electric field strengths (E/N)lim obtained from the present measurements are in good agreement with previous literature values.