Wave processes during type III solar radio burts : 2D PIC simulations

Nonlinear wave interactions as well as wave transformation processes on random plasma density inhomogeneities are thought to play a central role in electromagnetic wave radiation during type III solar radio bursts, in particular by generating radio waves at both the plasma frequency ω_p and its harmonic 2ω_p. Large-scale and long-term 2D Particle-In-Cell (PIC) simulations involving an electron beam generating upper-hybrid wave turbulence have been shown (e.g. Krafft et al. 2024 ApJL 967 L20) to be an efficient tool to study mechanisms as electrostatic decay, electromagnetic decay, wave coalescence, or conversion of modes at constant frequency.  Here a local and a global approach are combined to evidence such mechanisms in weakly magnetized solar wind plasmas, and to study their properties as a function of plasma parameters as the cyclotron frequency ω_c, the average level of random density fluctuations ΔN, and the ion-to-electron temperature ratio T_i/T_e.