CST Particle Studio Simulations of Coaxial Multipactor and Comparison With Experiments

Using CST Particle Studio, we simulate the evolution of the multipactor, beginning with a single seed electron inside a coaxial waveguide. Upon impact with either the outer or inner metallic wall, the primary electron is removed and the emitted secondary electrons are allowed to have a realistic 3-D velocity distribution. It is found that the single electron evolves very quickly into an axisymmetric distribution. The radial distribution of the multipactoring electrons is broad and very different from the infinitesimally thin multipactor electron sheet that was often assumed in previous models. The simulated threshold voltage for the onset of multipactor was compared with published experiments, and the level of agreement was found to depend on the secondary electron yield model chosen.