Fig. 1. Photocathode model

Fig. 2. Visual simulation result of Geant4

Fig. 3. Quantum yield of secondary electron

Fig. 4. Percentage of secondary electron

Fig. 5. Energy distribution of secondary electron emission of CsI photocathode. (a) 100 nm CsI film irradiated by X-rays with different energies; (b) CsI films of different thicknesses irradiated by 5 keV X-ray

Fig. 6. Position distributions of secondary electron emission of CsI photocathode. (a) 100 nm CsI film irradiated by X-rays with different energies; (b) CsI films of different thicknesses irradiated by 5 keV X-ray and position of secondary electron emitted by 100 nm CsI with 5 keV X-ray irradiation

Fig. 7. Distributions of secondary electron emission of CsI photocathode. (a) Angular distribution; (b) time distribution

Fig. 8. Object-surface electron distribution

Fig. 9. Electron optical system structure

Fig. 10. Image-surface distortion caused by first temporal focusing electrode. (a) Focusing electric field is too strong; (b) focusing electric field is too weak

Fig. 11. Image-surface distortion caused by first fade electrode. (a) Fade electric field is too strong; (b) fade electric field is too weak

Fig. 12. Electron tracks in time/space direction (non-isotropic)

Fig. 13. Image-surface electron distribution

Fig. 14. Simulation results based on CST's own generator. (a) Object-surface electron distribution; (b) image-surface electron distribution