A generalized two-dimensional flow-radiation coupled model to extract power from a gasdynamic laser is proposed. The model is used for the study of power extraction from a 9.4-μm CO2 downstream-mixing gasdynamic laser, where a cold CO2+H2 stream is mixed with a vibrationally excited N2 stream at the nozzle exits. This model is developed by coupling radiation with the two-dimensional, unsteady, laminar and viscous flow modeling needed for such systems. The analysis showed that the steady-state value of 9.4-μm intensity as high as 5×107 W/m2 can be obtained from the system studied. The role of H2 relaxant in the power extraction process has also been investigated.