TEMPORAL EVOLUTION OF THE VIBRATIONAL-EXCITATION WITHIN THE X1-SIGMA-G-COLUMN OF A PULSED ELECTRIC-DISCHARGE( STATE OF N2 IN THE POSITIVE)

The vibrational excitation to v = 1 level of the ground electronic sta te X1SIGMA(g)+ of nitrogen was measured in a positive column during th e 40-mus pulsed electric discharge, and in the afterglow. The discharg e was operating at 6 Torr pressure and at current densities in the ran ge 0.7-6.4 A/cm2. Temporal evolution of vibrational excitation was mea sured using coherent anti-Stokes Raman scattering (CARS). Vibrational temperatures were found to range from 700 to 4000 K. The results are i n fair agreement with model calculations based on energy transfer to v ibrational excitation. Vibrational temperatures of the X1SIGMA(g)+ sta te, obtained from direct CARS measurements, were up to a factor of 3 b elow those deduced from the second positive system emission.