Experimental data are analyzed on statistics of plane wave intensity fluctuations within the range of β0 parameter values from 6 to 18. Comparative analysis of high—order moments and histograms with theoretical models is carried out. The experimental moments exceed the available asymptotic values and become saturated within the range of β0 values from 7 to 18 at practically unchangeable level for the relative rms values of β fluctuations about 1.16÷1.17. The histograms of instantaneous values of the intensity are well approximated by K—distribution. Based on the experimental data the mean number of channels, N, for multi—beam propagation through the turbulent atmosphere, is related to the value of β0 parameter: N = 6 or 7 for β0 = 7 to 18.