Effect of temperature on the uniform field breakdown strength of electronegative gases

In general, the electron attachment rate constant k_a (〈ε〉, T), as a function of the mean electron energy 〈ε〉 and temperature T for electronegative gases which attach electrons nondissociative ily, decreases greatly with T from room temperature to T≲600 K, while the k_a (〈ε〉, T) of electronegative gases which attach electrons dissociatively increases with increasing T. Based on recent studies at our laboratory on k_a (〈ε〉, T), we investigated the variation with T (∼295-575 K) of the uniform field breakdown strength, (E/N)_lim, for three classes of electronegative gases: (a) gases such as c-C₄F₈ (and c-C₄F₆, 1-C₃F₆) which attach strongly low-energy (≲1 eV) electrons nondissociatively and for which k_a (〈ε〉, T) decreases precipitously with T above ambient: (b) gases such as C₂F₆ and CF₃Cl which attach electrons exclusively dissociatively and whose k_a (〈ε〉, T) increases with T; and (c) gases such as C ₃F₈ and n-C₄F₁₀ which attach electrons both nondissociatively and dissociatively over a common low-energy range and whose k_a (〈ε〉, T) first decreases and then increases with T above ambient. The (E/N)_lim(T) has been found to decrease significantly with T for (a), to decrease slowly with T for (c), and to increase slightly with T for (b). These changes in (E/N) _lim follow those in k_a (〈ε〉, T). A similar behavior is expected for other electronegative gaseous dielectrics in the respective three groups.