Two-Surface Multipactor in a Coaxial Transmission Line

Multipactor effect in a coaxial transmission line was studied theoretically and numerically. The results show that significant radio frequency breakdown likely originates from gas desorption in the material and further gas ionization induced by electrons. The multipactor effect using different surface gas pressures was analyzed with particle-in-cell simulations. The simulation results indicate that plasma originating from locally desorbed gas causes significant power reflection and absorption. At the same time, plasma electrons play a more significant role than plasma ions in the multipactor process. A numerical method such as the one used here can thus be used to predict whether radio frequency breakdown can be caused by the multipactor effect.