Beam-plasma instability in the presence of low-frequency turbulence

General equations are derived for a linear beam-plasma instability in the presence of low-frequency turbulence. Within a ’’quasilinear’’ statistical approximation, these equations contain Langmuir waves scattering, diffusion, resonant and nonresonant anomalous absorption, and a ’’plasma laser’’ effect. It is proposed that naturally occurring density irregularities in the solar wind may stabilize the beam-unstable Langmuir waves which occur during Type III solar radio emissions.