Fig. 1. Dumbbell type five-gap cavity

Fig. 2. Transverse electric field distribution of multi-gap cavity (a) TM₁₁ mode, (b) TM₃₁ mode

Fig. 3. Axial electric field distribution of five-gap cavity (a) TM₃₁-2π mode, (b) TM₃₁-1/4π mode, (c) TM₃₁-2/4π mode, (d) TM₃₁-3/4π mode, (e) TM₃₁-π mode

Fig. 4. Five-gap cavity of TM₁₁ mode (a) A 3D model of five-gap cavity, (b) transverse electric field distribution

Fig. 5. Influence of the fabrication tolerance of structure parameters on frequency (a) TM₃₁ mode, (b) TM₁₁ mode

Fig. 6. Influence of the fabrication tolerance of structure parameters on R/Q (a) TM₃₁ mode, (b) TM₁₁ mode

Fig. 7. Axial electric field distribution of output cavity (a) initial output cavity, (b) improved output cavity

Fig. 8. Electric field distribution of the initial and improved output cavity (a) axial electric field distribution, (b) transverse electric field distribution

Fig. 9. A 3D PIC simulation model of beam-wave interaction system

Fig. 10. Variation of the output power with typical parameters

Fig. 11. Output characteristics of the EIK at a frequency of 95 GHz (a) output signal versus time, (b) frequency spectrum of the output signal, (c) phase space portrait of the particle energy distribution, (d) beam bunching sketch

Fig. 12. Transmission characteristics of the sheet beam (a) The beginning of the high frequency system, (b) The end of the high frequency system