Heat current and anisotropy-driven instabilities in connection with the solar wind

The modification of two anisotropy-driven instabilities by a heat current is discussed in connection with solar wind models and observed solar wind characteristics. In both cases the mere existence of a third moment of the electron distribution has a destabilizing effect, though of a strongly different magnitude. Typical fluid models are unstable. For observed solar wind parameters, one instability has a small growth rate; the other is rarely excited but then has a large growth rate.