Resonant laser discharge involving excited nitrogen atoms

The conditions for sustaining a nitrogen plasma at a constant pressure by radiation resonant with a transition between excited states of the N atom are discussed. The necessary radiation intensities are found. They may be much lower than in the nonresonant case. If they are, the plasma temperature also decreases. The transition reaches saturation because there is a lower limit on the range of laser beam diameters at which the plasma can be sustained.