Particle-In-Cell Simulation of Uniformly Loaded W-band Gyro-TWT to Study its Multi-Mode Beam-Wave Interaction Behavior

In this paper, the Particle-In-Cell (PIC) simulation of a uniformly loaded, operating in fundamental circular TE01 mode gyrotron Traveling Wave Tube (gyro-TWT) amplifier is studied for its beam-wave interaction behavior for its principle mode along with other possible competitive modes. The uniformly loaded section of RF circuit provides sufficient attenuation to suppress the spurious modes including competitive modes, e.g., TE11, TE21 and TE02 modes. The PIC simulation predicts a peak RF output power of ~ 135 kW at 92 GHz with a saturated power gain of ~ 50 dB and a bandwidth ~ 5%. The electronic efficiency is calculated as ~ 27% for 100 kV, 5A annular electron beam having unity pitch. The performance of the amplifier has been investigated with respect to electrical parameters including beam voltage and current, beam pitch, velocity spread, RF drive power, magnetic field, etc.