Neutral gas motions play a very important role in dynamics of the ionospheric plasma especially below the turbopause level (100-120 km). In particular, neutral gas turbulence can produce irregularities in the electron density at these altitudes. Because of strong collisional damping at the ionospheric levels not always theory of plasma instabilities can be used to explain generation of fluctuations in electron density. In this report we discuss small-scale irregularities resulted from turbulent mixing of the gas in the lower ionosphere. The irregularity length-scales were restricted to the inertial range of turbulence and were smaller than the local scale of mean plasma-density gradient (which was chosen about 10 km). We considered the irregularity spectra expected from measurements during rocket (or radar) experiments and their dependence on the intensity of turbulence. The consideration was based on an analytic expression for the 3D spectrum of the fluctuations induced by the neutral turbulence in the ionosphere. The derivation of this expression from three-fluid equations is briefly described in the report. It was taken into account that spectrum of random velocity field of gas obeys the power law of Kolmogorov turbulence. The expression gave opportunity to write a formula for evaluation of the rms level of electron-density fluctuations in the given wave-number range. Variability of the 1D spectra expected from experiments was analysed for an irregularity layer in the altitude range 95-105 km (when the magnetic dip angle was 65°45') under intensification of turbulent mixing (the mean rate of turbulent energy dissipation increased from 10 to 100 mW/kg). It was shown that the enhancement of turbulence results in the rise of the rms fluctuation level and in decrease in the slope of irregularity spectrum. The fluctuation level (for the irregularities with length-scale smaller 500 m) near 95 km altitude increased from 2.7 to 2.8 % and near 105 km from 4.4 to 5.0%. If the irregularity spectrum is approximated by a simple power law then the power index increased from –2.12 to –1.95 for h=95 km and from –1.97 to –1.82 for h=105 km. The obtained results are explained by decreasing of the dissipation length-scale from 14.4 to 8.1 m (h=95 km) and from 54.1 to 30.4 m (h=105 km) under the rise of the dissipation rate. The weak change in the fluctuation level results from more important role of turbulent motions with small wave-numbers (large length-scales) in generation of the irregularities.