Analytical and PIC Simulation Studies of a Megawatt Class Gyrotwystron Amplifier.

In this paper, the analytical and particle-in-cell (PIC) simulation studies of an X -band megawatt class gyrotwystron have been presented. The device employs a tapered output waveguide to achieve stability against self-start oscillations due to azimuthally asymmetric modes, including the fundamental harmonic TE11 and TE21. A full nonlinear self-consistent, single particle, multimode, and multiharmonic, transient code has been developed to study the beam–wave interaction behavior. Furthermore, the device is simulated for studying its transient behavior using a commercial PIC code “CST Particle Studio.” This predicts the saturated RF power of $\sim 20$ MW in the fundamental TE01 mode and $\sim 1$ MW in the TE02 ( $s = 2$ ) mode, which is a self-generated spurious oscillation in the output section. The saturated gain is calculated as $\sim 24$ dB with a power conversion efficiency of $\sim 20$ % for a relativistic electron beam having 7% axial velocity spread. [ABSTRACT FROM PUBLISHER]