Top: some quantities related to the 1D wind equilibrium. Bottom: amplitude (in logarithm) of the unstable Fourier mode k_x = π/10 as a function of time. The background equilibrium is a laminar 1D wind computed for μ_eq = 10⁻³. Blue and green lines are, respectively, the surface density and vertical magnetic field perturbation. The blue dashed lines delimits the linear growth phase.