Development of PIC-FDTD code for beam-wave interaction study in ‘PASOTRON’

Plasma-assisted high power microwave source `PASOTRON' is being developed at a few places internationally to utilize plasma channel transport of the beam through Slow Wave Structure (SWS) to significantly reduce the size and weight in conventional linear high power microwave (HPM) sources by eliminating the need for the applied axial magnetic field [1-2]. In this device, very strong non-linear interaction between electron beam and electromagnetic wave can occur, thus making analytical design very cumbersome. Consequently, a particle simulation code is very much required to make its design simpler. We have made an efforts to study beam wave interaction in plasma filled SWS, which is a backward wave oscillator (BWO). The aim is to develop a particle-in-cell finite-difference-time-domain (PIC-FDTD) code [3] using MATLAB for the simulation of beam-wave interaction in the PASOTRON. The updating equations for electromagnetic fields are formulated using FDTD in cylindrical coordinate system since the SWS geometry is axially symmetric. In order to examine the field configuration in 3D, a field solver is implemented using the BOR-FDTD (Body of revolution FDTD) [4]. The results are being compared with MAGIC [5] tool software to validate the analysis. The results of this analysis will be presented.