Electrical and thermal conductivities of high-temperature CO2–CF3I mixture and transient conductance of residual arc during its extinction process

Fundamental properties of CO 2 mixed with CF 3 I were investigated in terms of (i) electrical and thermal conductivities at temperatures up to 30 000 K, (ii) a decay process of an arc conductance around a current zero under a free transient-recovery-voltage condition and (iii) an arc extinguishing capability in a thermal re-ignition region. The electrical conductivity at temperatures below 10 000 K proved to increase gradually with the admixture amount of CF 3 I. The thermal conductivity, in particular around 7000 K, was found to have marked dependence on the CF 3 I concentration. The result for the decay process of the residual-arc conductance under the free transient-recovery-voltage situation showed that the arc conductance attenuated more rapidly for CO 2 mixed with CF 3 I at concentrations above 0.9 than for pure CO 2 . The mixture gas having the same concentrations was also revealed to cause the arc to be extinguished under a higher transient-recovery voltage than pure CO 2 .