The flux as a function of CP for three-dimensional bunches. The purple solid line, red dotted–dashed line, black dashed line, and blue dotted line indicate φ _t = 0.1/γ, 1/γ, 5/γ, and 10/γ, respectively. We adopt below physical parameters: γ = 100, ρ = 10⁷ cm, ω = ω _c , Δθ _s = 10⁻³.