Double Probe Measurements of Ionization in Active Nitrogen

Abstract

Electron temperatures and ion densities have been measured in nitrogen afterglows in a flow system at short times after the discharge. In pure nitrogen a maximum occurs in the ionization density and in the electron temperature at 5 to 10 msec after the discharge. The position of this maximum coincides with the visible short‐duration nitrogen afterglow in which N₂⁺ emission is prominent. Small amounts of added impurity decrease this ion density but cause an increase in the ion density at longer times, reaching a second maximum at 80 to 100 msec after the discharge. These results show that ions and electrons are being produced continuously in nitrogen afterglows and that the rate of production is affected strongly by impurities.