Beam-wave Interaction Analysis of X-band Gridless Reltron

Abstract

In this work, particle in cell (PIC) simulation study has been performed to observe the operating characteristics of the highly efficient gridless-reltron in X-band. A 3D PIC code of gridless reltron is designed using CST microwave studio. The RF interaction structure of the Gridless-reltron is a well-known linac structure i.e. side-coupled cavity (SCC). In the reltron, three modes are excited named as 0–mode, $\pi $/2-mode and $\pi $-mode. The $\pi $/2-mode is selected as the operating mode because it is unstable and it grows in amplitude. PIC simulation predicts that the modeled gridless reltron with the beam current of 200 A and a total 250 kV as a tube voltage produces a microwave power of $\sim 13$ MW at 8.56 GHz with a pulse width of $3.2\,\mu \sec $ and efficiency of $\sim 26\%$, in the presence of a relatively low guiding magnetic field of 0.40 T.