Spatial distribution of the gain and temperature across the flow in a slit-nozzle supersonic chemical oxygen-iodine laser with transonic and supersonic schemes of iodine injection

Spatial distributions of the gain and temperature across the flow were studied for transonic and supersonic schemes of the iodine injection in a slit-nozzle supersonic chemical oxygen-iodine laser as a function of the iodine and secondary nitrogen flow rate, jet penetration parameter, and gas pumping rate. The mixing efficiency for supersonic injection of iodine (∼0.85) is much larger than for transonic injection (∼0.5), the maximum values of the gain being ∼0.65%/cm for both injection schemes. Measurements of the gain distribution as a function of the iodine molar flow rate nI₂ were carried out. For transonic injection, the optimal value of nI₂ at the flow centerline is smaller than that at off axis locations. The temperature is distributed homogeneously across the flow, increasing only in the narrow boundary layers near the walls. Opening a leak downstream of the cavity in order to decrease the Mach number results in a much larger mixing efficiency (∼0.8) than for a closed leak.