The multipactor effect is a microwave breakdown discharge occurring in vacuum conditions caused by the formation of an electron avalanche. The avalanche is created when high energy electrons collide with the walls of the device, releasing secondary electrons. This results in the creation of an electron plasma which degrades the response of the component.
With Spark3D the user can perform full numerical simulations of the multipactor effect considering the 3D EM field distribution. This is done by launching electrons in the component, tracking their trajectories and checking the evolution of the electron number with time.