Correlations of Deflection Angles of a Laser Beam in a Hot Turbulent Jet of Air: Theoretical Determination and Experimental Measurement of the Structure Coefficient of Refractive Index Fluctuations

Using the geometrical optics approximation, a theoretical prediction of the deflection angle correlation of a laser beam propagating in a hot turbulent jet is found as a functional form of the turbulent spectrum of the refractive index fluctuations. By applying the modified Von Karman model and Tatarskii model, the structure coefficient of the refractive index and the deflection angle correlation of the laser beam are then computed by means of a numerical procedure. Experiments to measure the structure coefficient are performed. A good agreement between the experimental results obtained and the theoretical predictions demonstrates the validity of the theoretical approach.