Abstract
When impurity gas exists in a discharge lamp, both the breakdown voltage and the positive column field strength increase. Value (E2-E02)/E02, which means an increasing ratio of electron energy loss by impurity gas to that by main gas, is proportional to impurity gas concentration, where E and E0 are the electric field strength in positive column with and without impurity gas, respectively. This ratio depends on electron energy loss mechanism by impurity gas. In Penning mixture gas, electrons lose their energy by exciting main gas atoms to their metastable levels. The metastable atoms lose their energy by the second kind collision with impurity gas molecules. On the otherhand, in the positive column with a current density between 5×10-3 A/cm2 and 5×10-2 A/cm2, electrons lose their energy by direct collision with impurity gas molecules. Impurity gas affects more strongly on the positive column field than on the breakdown voltage.
