Stimulated emission from the recombining afterglow of an electron-beam discharge in several atmospheres of helium

Stimulated emission from excited states of He₂ has been observed as a consequence of the collisionally stabilized recombination of ${\mathrm{He}}_2^{+}$ ions with electrons in the afterglow of a pulsed gigawatt electron‐beam discharge into 3 atm of helium. Peak gains of the order of 0.04 cm⁻¹ were found in components of the ${\text{3s}}^3{\Sigma }_u^{+}{\text{→ 2p}}^3{\Pi }_g$ transition of He₂ in the 6400‐Å region by directly measuring the time‐resolved gain spectra using a tunable dye laser.