Particle-in-cell simulation of a RBWO with experimental voltage input pulse and external magnetic field

Abstract

An experimental S-band Relativistic Backward Wave Oscillator (RBWO) which uses Kilo Ampere Linear Injector (KALI) which is a 30GW system and for this system voltage pulse has been simulated using Particle-In-Cell (PIC) code. The motivation of this paper is to study the effect of replication of KALI input pulse and magnetic field profile, obtained from experimental data into the PIC simulations, which in turn will help in optimizing the design of the device. The actual KALI pulse of ~550kV peak voltage, 100ns duration and 20ns rise time is simulated as a temporal function of the voltage instead of a conventional dc pulse. The experimental magnetic field with peak value of ~0.5T is not constant and changes along the longitudinal axis (z). Hence, the same is expressed in the PIC code as a spatial function of the z-coordinate instead of a constant value. The output power from the PIC simulations with KALI input pulse is found to be in close agreement with the experimental results against the output power obtained from the PIC simulations with conventional dc pulse.