  Empirical models of the solar chromosphere show intense electron heating
immediately above its temperature minimum. Mechanisms such as resistive
dissipation and shock waves appear insufficient to account for the persistence
and uniformity of this heating as inferred from both UV lines and continuum
measurements. This paper further develops the theory of the Farley-Buneman
Instability (FBI) which could contribute substantially to this heating. It
expands upon the single ion theory presented by Fontenla (2005) by developing a
multiple ion species approach that better models the diverse, metal-dominated
ion plasma of the solar chromosphere. This analysis generates a linear
dispersion relationship that predicts the critical electron drift velocity
needed to trigger the instability. Using careful estimates of collision
frequencies and a one-dimensional, semi-empirical model of the chromosphere,
this new theory predicts that the instability may be triggered by velocities as
low as 4 km s^-1, well below the neutral acoustic speed. In the Earth's
ionosphere, the FBI occurs frequently in situations where the instability
trigger speed significantly exceeds the neutral acoustic speed. From this, we
expect neutral flows rising from the photosphere to have enough energy to
easily create electric fields and electron Hall drifts with sufficient
amplitude to make the FBI common in the chromosphere. If so, this process will
provide a mechanism to convert neutral flow and turbulence energy into electron
thermal energy in the quiet Sun.
