Transient physics of multipactor induced plasmabreakdown near a dielectric surface

Multipactor and plasma ionization breakdown near a dielectric microwave window are limiting factors for high power microwave sources with applications in space-based satellite communications. In this work, we will present the physics of higher harmonic (HH) generation of the normal electric field in multipactor-induced plasma breakdown using kinetic particle-in-cell simulations and a theoretical model. The observed harmonic frequency in simulations is around ten times the fundamental rf driving frequency (1GHz). The theoretical model reveals that the interaction of beam-like secondary electrons injected into the plasma[JV1] is the fundamental mechanism behind the HH generation [Wen et al. Physical Review Letters, (2022)]. With pressure increasing from 0.2Torr to 1Torr, the HH phenomenon disappears. Additionally, a propagating multilayer-like structure is observed for helium discharges. The physical mechanism is attributed to the response of light ions to two neighboring reversed normal electric fields and localized space charge [Wen et al, Applied Physics Letter, 119, 264102 (2021)].