Dispersion plots of the wave spectral magnetic energy densities log_{10}(∣*B*_{zk}(*ω*_{k}, *k*_{x})∣^{2}) as a function of the normalized frequency *ω*_{k}/*ω*_{p} and parallel wave vector *k*_{x}*λ*_{D}, for a homogeneous plasma with Δ*N* = 0 and a plasma with density fluctuations (Δ*N* = 0.05). The simulations used are the same as in Figures 2–3. Panel A: dispersion plots for Δ*N* = 0.05, at *ω*_{p}*t* = 680, 2020, and 3100, computed with the “large” simulation box; a zoom of the frequency wave-number domain 0.9 < *ω*_{k}/*ω*_{p} < 1.2 and ∣*k*_{x}*λ*_{D}∣ < 0.02 is shown for *ω*_{p}*t* = 3100 in the bottom right corner. Panel B : dispersion plots obtained using the “smaller” box, at *ω*_{p}*t* = 2020, for Δ*N* = 0 (left) and Δ*N* = 0.05 (right). Panel C: dispersion plots at asymptotic times for Δ*N* = 0 (left, *ω*_{p}*t* = 7960) and Δ*N* = 0.05 (right, *ω*_{p}*t* = 6340); the “smaller” simulation box is used. The same color bar holds for all plots of panels (A), (B), and (C). All variables are normalized.