Pitch-angle mean-square variations 〈(Δμ)²〉, as a function of the normalized time tΩ for the M_s ≃ 10 and M_A ≃ 10 simulation. The initial pitch angle distribution is isotropic with r_L/L_box ≃ 8 × 10⁻³. The blue and red curves show results obtained using 10³ and 10⁴ particles, respectively. The gray dotted line marks the saturation value.