Unraveling Plasma Characteristics and Breakdown Mechanism in Nanosecond-Pulsed Dielectric Barrier Discharge

Nanosecond-pulsed dielectric barrier discharges (DBDs) have gained significant attention for its promising applications in various fields. More systematic investigations are necessary to better understand the fundamental processes of pulsed DBD. In this study, the characteristics and the initial breakdown mechanism of atmospheric nanosecond-pulsed DBD are investigated. The electric field-induced second harmonic (E-FISH) technique is employed to investigate the electric field within the discharge gap. Additionally, the effects of pulse amplitude and pulse repetition rate on discharge characteristics, particularly the electric field, are analyzed. The results indicate that an increase in pulse amplitude leads to higher breakdown currents and a more pronounced reverse electric field peak, whereas the pulse repetition rate has a minimal effect on discharge behavior. A 2-D fluid model is developed to simulate discharge dynamics and analyze the spatiotemporal evolution of particles. Based on both experimental and simulation results, the discharge process is characterized by three distinct stages: Stage I (discharge breakdown), Stage II (surface charge accumulation), and Stage III (surface charge neutralization). The breakdown mechanism is further elucidated by examining the role of residual charges near the dielectric layer, which enhances the local electric field and facilitate the generation of secondary electrons, leading to ionization and subsequent discharge establishment.