Upstream and downstream multipactor of dielectric window by electromagnetic PIC simulations

By using the electromagnetic Particle-In-Cell method, the multipactor of the dielectric window on the upstream side is observed directly even without presetting extra normal electric fields and compared to that on the downstream side. This paper shows: First, with the initial emission of electrons to provide extra normal electric fields, the secondary electron avalanche is much faster than that on the downstream side. Second, even without the initial emission of electron to provide extra normal electric fields, the secondary electron avalanche occurs on the upstream side, while it is nowhere to be found on the downstream side.