Phase portraits for ψ_⋆0 = 70° and ϵ_⋆d = 0.1 (a), 1.0 (b), and 10.0 (c) displayed on the unite sphere. These portraits were generated by plotting level curves of the perturbing Hamiltonian from Eq. (20) with |l₁| = 1. The orientations of ${\hat{\mathit{s}}}_{\star }$ and ${\hat{\mathit{l}}}_{\mathrm{d}}$ are shown, along with the norm of the principal plane. Equilibria are marked by colored points, which correspond to the equilibrium solutions identified in Fig. 2a.