  We investigate electrostatic plasma instabilities of Farley-Buneman (FB) type
driven by quasi-stationary neutral gas flows in the solar chromosphere. The
role of these instabilities in the chromosphere is clarified. We find that the
destabilizing ion thermal effect is highly reduced by the Coulomb collisions
and can be ignored for the chromospheric FB-type instabilities. On the
contrary, the destabilizing electron thermal effect is important and causes a
significant reduction of the neutral drag velocity triggering the instability.
The resulting threshold velocity is found as function of chromospheric height.
Our results indicate that the FB type instabilities are still less efficient in
the global chromospheric heating than the Joule dissipation of the currents
driving these instabilities. This conclusion does not exclude the possibility
that the FB type instabilities develop in the places where the cross-field
currents overcome the threshold value and contribute to the heating locally.
Typical length-scales of plasma density fluctuations produced by these
instabilities are determined by the wavelengths of unstable modes, which are in
the range $10-10^2$ cm in the lower chromosphere, and $10^2-10^3$ cm in the
upper chromosphere. These results suggest that the decimetric radio waves
undergoing scattering (scintillations) by these plasma irregularities can serve
as a tool for remote probing of the solar chromosphere at different heights.
