Three-dimensional numerical simulation of multipactor in open antenna structures

A three-dimensional numerical simulation method of multipactor in open-structured high-power microwave systems is presented in this work. This method considering the perfect absorption of electrons at open boundaries, the commonly used absorption method with perfect-matched layers in electro-magnetic simulations has been modified and an improved absorbing boundary has been established which avoids the instability of computation. Together with the electromagnetic Particle-In-Cell technologies and the secondary electron emission models, the high-diffusion effect and the nonlinear dynamics of electrons in multipactor phenomena are intuitively investigated for the first time in open structures. As an illustration, the simulation results of a spiral antenna are provided, which reveals the transient evolution of electron accumulation in this typical open structure. By analyzing the tendency of the evolution, the multipactor threshold of the antenna has been successfully estimated.