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

In general, the electron attachment rate constant, ka ( , T), as a function of the mean electron energy and temperature T for electronegative gases which attach electrons nondissociatively decreases greatly with T from room temperature to T , T), we investigated the variation with T (~295-575K) of the uniform field breakdown strength, (E/N)Qim, for three classes of electronegative gases: (a) gases such as c-C4F8 (and c-C4F6, 1-C3F6) which attach strongly low-energy ( , T), decreases precipitously with T above ambient; (b) gases such as C2F6 and CF3Cl which attach electrons exclusively dissociatively and whose k ( , T) increases with T; and (c) gases such as C3F8 and n-C4F10 which attach electrons both nondissociatively and dissociatively over a common low-energy range and whose ka ( , T) first decreases and then increases with T above ambient. The (E/N Qim(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)Qim follow those in ka ( , T). A similar behavior is expected for other electronegative gaseous dielectrics in the respective three groups.