Electrical breakdown of N2O, SF6 and N2O/SF6 mixtures

Measurements of static breakdown voltages were made for SF6 and N2O/SF6 mixtures containing between 1% and 50% SF6 by volume for values of Nds within the range 1023 < Nds < 1024 m¿2 (where N is the gas number density and ds the sparking distance). These results, together with earlier data on N2O, show that the departures from Paschen´s law become smaller as the percentage of SF6 in the mixture is increased over the range from 0 to 10% becoming negligible above about 6%. These results agree with predictions made on the basis of the ion-molecule reactions occurring in these gases. The dielectric strength of a 37% mixture was found to be about 83% of that for SF6 alone, and it is shown that, for this mixture, an increase in total pressure of about 20% gives the same dielectric strength as SF6 alone with a saving in cost of about 50%.