Plasma waves in the Earth's electron foreshock: 2. Simulations using time-of-flight electron distributions in a generalized Lorentzian plasma

This study considers the It:vel of occurrence of nonlinear wave-wave intera ctions in foreshock nonthermal plasma and whether such interactions are sig nificant in producing observed electromagnetic emissions;To this end, we pe rformed two-dimensional electromagnetic particle-in-cell (PIC) simulations using the time-of-flight electron distribution model described in the paper proceeding this [Yin et al., this issue], and input parameters based on tw o sets of Wind/3DP distribution measurements made when narrowband and broad band waves were detected by the Wind/WAVES instruments. In the simulations we limited the wave energy density to W less than or similar to 10(-3), a v alue inferred from the largest wave amplitude detected by Wind. We consider the dynamics of narrowband and broadband wave instabilities, focusing on w ave-coupling processes in the presence of foreshock hot ions as well as the most intense narrowband waves, which are the most likely candidates for pr oducing the detected electromagnetic emissions. Results are compared with r ecent Wind measurements. We showed that when foreshock conditions exist, qu asilinear diffusion dominates the instabilities, that weak wave coupling do es not prevent beam flattening, and that Ilo discernible wave backscatterin g occurs. The study indicates that the weak nonlinearity of foreshock elect rostatic waves in a homogeneous plasma and in the presence of foreshock non thermal electrons and moderate beam parameters is not responsible for the g eneration of electromagnetic emissions at either the fundamental or the sec ond harmonic of the plasma frequency.