Physics of Superpulses in Storage Ring Free-Electron Lasers

Figure 1

Evolution of a superpulse in OK-4/Duke SR FEL predicted by uvfel code. Intracavity optical laser beam energy (black) and peak power (red) are plotted in log-scale (left), and relative RMS e-beam energy spread (blue) is plotted in linear scale (right). Operational parameters: E_o = 650 MeV, 𝐼_𝑒 = 36.3 A, λ = 237 nm, N_w = 33.5, N_D = 10.75, Q_s = 0.0094, σ _γo/γ =1.5.10⁻³, σ _zo = 2.42 cm, starting peak gain G_o = 16.5%, optical cavity losses are 2% per turn (see [8] for details). Inset shows peak power growth (in linear scale) for turns 150–200.