Abstract: A wind tunnel in which high energy laser beam impingement studies can be ducted such that beam distortion and degradation is substantially precluded. Uniform, low turbulence flow in which thermal blooming, creation of wakes is substantially eliminated is attained by providing an improved elongated cylindrical settling chamber having a gradual turning radius. A transverse aerodynamic window is located in the low velocity flow turning region of the settling chamber which allows the entry of the laser beam and the exhaust of a turbulent sonic free-jet constituting 10 percent of the total fluid flow through the wind tunnel.