In Fig. 5, the pitch-angle Fokker-Planck coefficient is shown as a
function of the normalized simulation time, τ = Ωt. After the initial
free-streaming phase, most values become (almost) constant,
while the initially higher values still oscillate. At τ = 102, the
final, diffusive values for Dμμ are taken that are used in the following
sections. It should be noted, however, that Dμμ is slightly
decreasing (with approximately ∝τ−0.14) so that the values for
Dμμ are somewhat overestimated, in agreement with the results
shown below.