Fig. 1. Definition of the (a) Plane; (b) Rogowski; (c) Bruce; (d) elliptical electrode profiles for UED.

Fig. 2. Field enhancements of 90° Rogowski, Bruce, and elliptical electrode: (a) The central axis; (b) along the curved edge of cathode.

Fig. 3. Geometry of the new high voltage electrode.

Fig. 4. Effect of dimensional change of center plane area on field enhancement when the overall radius is constant.

Fig. 5. Field enhancement effect at different cathode-anode spacings: (a) Field enhancement on the axis; (b) field enhancement along the cathode surface.

Fig. 6. Influence of the electrode configuration on field enhancement: (a) Asymmetric electrode configuration; (b) symmetric electrode configuration.

Fig. 7. Electric field distribution at the anode pinholes: (a) Without TEM grid; (b) 50 mesh TEM grid; (c) comparison of different meshes of TEM grid.

Fig. 8. Design of anode pinholes.

Fig. 9. Schematic diagram of anode movable ultrafast electron diffractometer.

Fig. 10. Spatial distribution of electron source at time = 0.

Fig. 11. Effect of accelerating voltage, initial electron dispersion and number of electrons on the length of the electron pulse: (a) V = 10 kV, z = 0−5 mm; (b)V = 125 kV, z = 0−20 mm; (c)V = 10 kV, z = 0−20 mm; (d)V = 125 kV, z = 0−100 mm.

Fig. 12. Effect of accelerating voltage, initial electron dispersion, and number of electrons on beam spot size: (a) V = 10 kV, z = 0−0.02 m; (b)V = 125 kV, z = 0−0.02 m.

Fig. 13. Effect of magnetic lens on electronic pulse length: (a) n = 1000; (b) n = 10000.

Fig. 14. Effect of magnetic lens on beam spot size: (a) n = 1000; (b) n = 10000.