Research on X-band inner coaxial disk-loaded relativistic backward-wave oscillator
The relativistic backward-wave oscillator(RBWO) with inner coaxial disk-loaded slow-wave structure(SWS) is studied.The dispersion relation of the SWS is deduced by using the Borgnis's potential function method according to Maxwell's equation and Floquet theory.Numerical analysis is carried out and the dispersion curves are gotten.The beam-wave interaction of the device is simulated and optimized by PIC method.The effect of the longitudinal magnetic field,the distance r_1 between beam and SWS,the depth r_2 of loaded-disk and the distance of two next disks are discussed in detail.The results show that increasing the periodic length can decrease the cut-off frequency and the operating frequency of the same mode and that the variation of the inner conductor radius almost has no effect on the operating frequency of RBWO.When the longitudinal magnetic field is 0.7 T,the periodic length 11 mm,the r_1 and r_2 are 2 mm,and the distance of two next disks is 3.6 mm,the peak output power and efficiency would be higher than 2.8 GW and 33.2% driven by 520 kV,8 kA electron beam with a suitable drift-tube in the SWS.