Effect of inhomogeneous microwave field on the threshold of multipactor discharge on a dielectric

Multipactor discharge on a dielectric (quartz) surface has been studied in a high-Q microwave resonator excited by TE01n mode in the 3-cm wavelength band. It is established that the discharge threshold significantly depends on the magnitude and direction of a ponderomotive force, which appears at the dielectric surface due to a gradient of the high-frequency potential. The force that repulses electrons from the surface leads to a significant increase in the threshold, whereas the attractive force decreases the threshold. Experiments confirm that a multipactor can arise in inhomogeneous electromagnetic fields in the absence of an external static field that returns emitted electrons to the dielectric surface.