Pulseless Corona in Negative Point to Plane Gap

The pulseless corona of a negative point to a plane gap in air was examined. At high pressures it behaves as a kind of abnormal glow discharge. By increasing the corona current, the reduced current density on the cathode surface increases from 267 µA/(cm·Torr) 2 at the onset to 490 µA/(cm·Torr) 2 just before the spark breakdown. The gas temperature of the negative glow shows also an increase in the range of 1050∼1170 K with increasing corona current. The current distributions on the plane electrode are similar for different values of the gap length. In the space gap near the plane electrode, at the moment of transition is equal to or greater than the electron attachment coefficient. This result can be used as a criterion for the occurrence of a transition from the negative pulseless corona to spark breakdown.