Fig. 1. Inner boundary condition of pipe shell

Fig. 2. Force and velocity of the electron in the plane of pole piece

Fig. 3. Distribution of magnetic field of 2 focusing system

Fig. 4. Distribution of electron at the pole piece exit

Fig. 5. Electron beam projection focused by T-shaped loaded vane compound pipe shell PPM focusing system

Fig. 6. Variation of magnetic field with the amount of loaded vanes

Fig. 7. Slow-wave structure parameters

Fig. 8. Variation of cooling parameters with R_L

Fig. 9. Electron beam projection focused by tooth-shaped loaded vane PPM focusing system