The Effect of Pressure on the Positive Point-to-Plane Discharge in ${\mathrm{N}}_2$, ${\mathrm{O}}_2$, C${\mathrm{O}}_2$, S${\mathrm{O}}_2$, S${\mathrm{F}}_6$, C${\mathrm{Cl}}_2$${\mathrm{F}}_2$, A, He, and ${\mathrm{H}}_2$

The voltages at which corona first appears in a 3-mm point-to-plane gap and the breakdown voltage of the gap have been determined with ${\mathrm{N}}_2$, ${\mathrm{O}}_2$, C${\mathrm{O}}_2$, S${\mathrm{O}}_2$, S${\mathrm{F}}_6$, C${\mathrm{Cl}}_2$ ${\mathrm{F}}_2$, A, He, and ${\mathrm{H}}_2$, and certain mixtures of these gases. This has been done with both positive and negative point polarity and over a pressure range of about 30 atmospheres. The types of corona which were observed are discussed and in particular the marked dependence of the positive point breakdown voltage on pressure in those gases which form negative ions.