Fig. 1. Schematic structure and principle of thermal field electron gun immersed in magnetic lens field

Fig. 2. Structures of three magnetic immersion lenses

Fig. 3. Distributions of axial magnetic field of three magnetic immersion lenses under same excitation

Fig. 4. Relationship between l/Cs and excitation intensity of lens Vr/NI2^［28］

Fig. 5. Structure of magnetic field immersed thermal field electron gun and electron beam trajectory

Fig. 6. Performance variation of magnetic field immersed thermal field electron gun with lens current

Fig. 7. Variation of reduced brightness of magnetic field immersed thermal field electron gun with lens current

Fig. 8. Schematic diagram of structure of magnetic filed immersed electron optical system and optical path under different working modes

Fig. 9. Experimental platform of magnetic field immersed thermal field electron gun

Fig. 10. Comparison between simulated and measured results of on-axis magnetic field in magnetic immersion lens

Fig. 11. Test results of saturation magnetic field in magnetic immersion lens

Fig. 12. Focusing process of beam spot

Fig. 13. Variation of effective beam current of electron gun with magnetic immersion lens excitation

Fig. 14. Variation of effective beam current of magnetic field immersed electron gun with extractor voltage

Fig. 15. Variation of effective beam current of magnetic field immersed electron gun with accelerator voltage