Laser propagation in a humid atmosphere: conduction dominated thermal blooming

A conduction dominated thermal blooming phenomenon of a powerful laser beam propagating in an unguided channel (humid atmosphere) is rigorosly investigated based on ray optics and taking into account the coupling between the beam and the medium along the propagation path. Transport coefficients are humidity- and temperature-dependent. We have derived the continuum value of refractivity N and the absorption coefficient σ of humid air under the form1.