Temporally and spatially resolved gain measurements are reported for near‐atmospheric CO2:N2:He glow discharges in a contoured planar electrode configuration. When suitably preionized by rows of electrically stressed dielectric interfaces, the entire interelectrode volume is filled with a uniform glow discharge for large ranges of capacitor energy, voltage, and gas pressure. The 10.59‐&mgr;m gain reaches a peak value of 2.8% cm−1in 2 &mgr;sec, and decays exponentially with a 20‐&mgr;sec time constant in near‐optimum laser mixtures of 60 Torr CO2, 180 Torr N2, and 60 Torr He. Peak gain is uniform over the transverse dimensions to within 5%. Mathematical expressions are developed which relate the small‐signal gain to thePandRbranch rotational quantum numbers in a linear fashion. This analysis shows that for optimized laser conditions the 00°1–10°0 population inversion is[inverted lazy s]1.8×1017 cm−3with a rotational temperature of[inverted lazy s]400 °K. This corresponds to a maximum 10.6‐&mgr;m optical storage density of[inverted lazy s]31 J/literand represents[inverted lazy s]17%of the electrical energy input to the discharge.