Modelling of free-electron maser based on two-dimensional distributed feedback

Abstract

The use of two-dimensional (2D) distributed feedback has been considered as a method of providing spatially coherent radiation from an oversized annular electron beam used to drive a ITEM based on a coaxial two-mirror cavity. The operation of the FEM when the interaction space is formed by a 2D Bragg input and a 1D Bragg output mirror separated by a regular section of the coaxial waveguide has been studied using the 3D Particle-in-Cell code MAGIC. The properties of the FEM are analyzed and discussed. The single mode operation of the FEM that uses a coaxial cavity is demonstrated and the design of a 2D Bragg FEM-oscillator based on a high-current accelerator is discussed