Simulation of Electron Beams with Nonuniform Particle Density for Traveling-Wave Tubes in Emittance-Dominated Regime

In the millimeter wave and terahertz regime, inclusion of beam emittance while designing a traveling-wave tube (TWT) is important as the effects of beam emittance dominates those of space charge. The beam emittance affects performance of the TWT as well as transport of the electron beam. In particular, the equilibrium particle distribution is not uniform in the emittance-dominated regime. To simulate transport of electron beams having the nonuniform particle density, the stationary beam distributions in constant magnetic field such as Kapchinsky-Vladimirsky (K-V), waterbag, and Gaussian, are used. The numerical simulations are conducted using a CST Studio Suite by importing the generated distributions into the simulations. The results show that the transport of stationary beam distributions is stable.