Four-wave Processes Involving Two Low Frequency Waves

Abstract

The probability is calculated for a four-wave process in which a Langmuir wave combines with two low frequency (ion sound) waves to produce another Langmuir wave or a transverse wave. The major part of the calculation involves relevant approximations to the quadratic and cubic nonlinear response tensors. An estimate based on observational data from the interplanetary medium suggests that the four-wave process may be significant in solar radiophysics.