3D Beam-Wave Interaction Study in a Dielectric Loaded W-band Gyro-TWT using MAGIC

In this paper, Particle-in-Cell (PIC) simulation study of a lossy dielectric loaded gyrotron travelling wave tube (gyro-TWT) amplifier operating in W-band is presented. The RF interaction region is loaded uniformly with a lossy dielectric to attenuate the potential backward wave oscillations (BWO's) caused by competing modes including the fundamental harmonic TE₁₁, TE₂₁, and second harmonic TE₀₂ modes. The complete RF interaction circuit of gyro-TWT is simulated using 3D PIC code "MAGIC" to study its beam-wave interaction behaviour. The simulation predicted a peak RF power of ~190kW in a fundamental TE₀₁ mode with a conversion efficiency of ~30% and a high gain of ~63dB for a non-spread gyrating 70kV, 9A electron beam.