Beam–Wave Interaction Analysis Inside an Azimuthally Partitioned Axially Periodic Disk-Loaded Coaxial Structure for Bifrequency MILO

Abstract

In this article, the electromagnetic (or RF) behavior of the azimuthally partitioned axially periodic metal disk-loaded coaxial structure was investigated using an equivalent circuit approach in the presence of the electron beam. In the analysis, the linearized Maxwell's fluid equation (also known as Vlasov-Maxwell's equation) was used to analyze the region in which the electron beam was present. The expression for the equivalent series inductance and shunt capacitance per unit length for the equivalent transmission line was derived in the electron beam present and absent case. The derived expressions include all the harmonics effects present inside the structure. Furthermore, the expression of the dispersion relation and temporal growth rate (TGR) was derived using the calculated equivalent series inductance and equivalent shunt capacitance. The output RF power and energy were also calculated analytically and validated through the PIC simulation. The results were compared with the already reported literature, and the relative error between them was below 5%. In addition, the effect of different beam parameters on the TGR behavior was also analyzed.