  In this study we discuss the excitation of low frequency plasma waves in the
lower-middle chromosphere region of loop footpoints for the case when the
plasma can be considered in a pre-flare state. It is shown, that among the
known semi-empirical models of the solar atmosphere, only the VAL (F) model
together with a particular set of basic plasma parameters and amplitudes of the
electric and magnetic fields supports generation of low frequency wave
instability. Our results show that it is possible to predict the onset of the
flare process in the active region by using the interaction of kinetic Alfven
and kinetic ion-acoustic waves, which are solutions of the derived dispersion
equation. The VAL (F) model allows situations when the main source of the
aforementioned instability can be a sub-Dreicer electric field and drift plasma
movements due to the presence of spatial inhomogeneities. We also show that the
generation of kinetic Alfven and kinetic ion-acoustic waves can occur both, in
plasma with a purely Coulomb conductivity and in the presence of small-scale
Bernstein turbulence. The excitation of the small amplitude kinetic waves due
to development of low threshold instability in plasma with relatively low
values of the magnetic field strength is also discussed.
