The CP fraction as a function of the angle between LOS and the trajectory plane. The blue line denotes the single particle and three-dimensional bunch case for φ _t ≲ 1/γ, where γ = 100 and ω = ω _c . The red lines indicate three-dimensional bunch case for φ _t > 1/γ, where dashed, solid, dotted–dashed, and dotted lines denote γ = 100, φ _t = 5/γ, ω = ω _c ; γ = 100, φ _t =10/γ, ω = ω _c ; γ = 10, φ _t = 10/γ, ω = ω _c ; γ = 100, φ _t = 10/γ, ω = 10ω _c , respectively. The other parameters are adopted as Δθ _s = 10⁻³ and ρ = 10⁷ cm.