Vlasov-Poisson simulations of electrostatic parametric instability for localized Langmuir wave packets in the solar wind

Recent observation of large-amplitude Langmuir waveforms during a type III event in the solar wind has been interpreted as the signature of the electrostatic decay of beam-driven Langmuir waves. This mechanism is thought to be a first step to explain the generation of type III radio emission. The threshold for this parametric instability in the typical solar wind condition has been investigated through 1D-1V Vlasov-Poisson simulations. We show that the amplitude of the observed Langmuir beatlike waveforms is of the order of the effective threshold computed from the simulations. The expected levels of associated ion acoustic density fluctuations have also been computed for comparison with observations