Nonlinear investigation and 3-D particle simulation of second-harmonic gyro-TWT with a mode selective circuit

Abstract

The beam-wave interaction behavior of a second-harmonic Ku-band high-power gyro-TWT comprising a mode selective RF interaction circuit has been investigated using a 3-D particle simulation code. The mode-selective RF circuit has been cut axially into four slices to restrain the electromagnetic modes not having m=2 symmetry. A self-consistent nonlinear large signal code has been developed to compute the field amplitude, power, energy, and phase of the gyrating beam. The amplifier gives a saturated peak power of ∼ 230 kW at 15.8 GHz for beam parameters of 80 kV and 20 A having a pitch of 1.1. The large signal gain of the device has been calculated as ∼ 16 dB for the beam spread of 14%. Further, the nonlinear findings have been validated against the Particle-in-Cell code that predicts the saturated output power of ∼ 193 kW in a circular TE21 mode at the desired operating frequency. © 1963-2012 IEEE.