Design and Simulation Study of Wraparound Couplers for Gyrotron Travelling Wave Amplifiers

In this paper, the design methodology of an input coupler for X band gyrotron amplifier (gyro-amplifier) has been presented along with a comparative study of 4-slots and 5-slots variant of couplers. In addition to the 3D modelling, the RF propagation characteristics have been studied through the CST microwave studio. The two different configurations of input coupler (4-slots and 5-slots) are incorporated in X-band gyrotwystron for Particle-in-cell (PIC) simulation study. The S
₁₁
and S
₂₁
of 4-slot input coupler have been found as -25.9 dB and -0.1 dB respectively and the S
₁₁
and S
₂₁
of 5-slot input coupler have been found as -31.5 dB and -0.09 dB respectively. Further, the performance of couplers is evaluated using the 3D PIC code CST particle studio.