O$_{2}(^{1}\Delta )$ Production and Oxygen-Iodine Kinetics in Flowing Afterglows for Electrically Excited Chemical-Oxygen-Iodine Lasers

Chemical oxygen-iodine lasers (COILs) achieve oscillation on the $^{2}$P$_{1/2}\to ^{2}$P$_{3/2}$ transition of atomic iodine at 1.315 $\mu $m by a series of excitation transfers from O$_{2}(^{1}\Delta )$. In electrically excited COILs, (eCOILs) the O$_{2}(^{1}\Delta )$ is produced in a flowing plasma, typically He/O$_{2}$, at a few to tens of Torr. eCOILs additionally differ from conventional systems in the large amount of O atoms produced due to electron impact dissociation. O atoms are advantageous in that they react with and dissociate I$_{2}$, but O atoms also quench I($^{2}$P$_{1/2})$. To some degree, the O atom density in the afterglow can be controlled by injecting NO or NO$_{2}$ which consumes O atoms. This also impacts O$_{3}$ production, particularly at higher pressures where quenching of O$_{2}(^{1}\Delta )$ by O$_{3}$ is problematic. In this paper, results from computational investigations using plug-flow and 2-dimensional plasma hydrodynamics models will be discussed for scaling laws in eCOIL systems for O$_{2}(^{1}\Delta )$ production. We will discuss O-atom management with NO/NO$_{2}$ additives and I($^{2}$P$_{1/2})$ production with I$_{2}$ injection. Scaling to higher pressures will be discussed where gas heating and O$_{3}$ quenching of O$_{2}(^{1}\Delta )$ become important.