Flux of particles coming from the line X = D, with D = 1.25 > D_crit. The two types of possible orbits are represented separately, with the same colour code as in Fig. 3. Top: unbounded trajectories of type T₃ are represented in blue. They approach a minimum distance equal to 1 but never reach it exactly (outer dashed circle, around which they can perform an arbitrary number of turns before going back). In the limiting case where ρ_C = 1 (black initial condition), the particle makes a infinite number of turns as ρ → 1. Bottom: unbounded trajectories of type T₁ are represented in red. They cross the characteristic radius ρ₀, at which their angular velocity is inverted (see the small loops). For initial positions Y_i tending to the black point, the minimal distance reached by the particle tends to ρ_cav = W₀(exp[−1]) (inner dashed circle, see (Eq. 37)). If we consider an infinite number of particles, this forms a cavity with radius W₀(exp[−1]) (grey disc).