No abstract

Packed bed reactor (PBR) isthe commonly used configuration in Plasma-catalysis and the plasma 
characteristics has been extensively investigated. The filled catalysts in PBR makes it challenging 
to carry out in-situ measurement of electric field, and few experimental data has been obtained. We 
investigated the surface streamer propagation and electric field distribution in a simplified PBR 
through simulations and experiments. The simplified PBR in the experiments is comprised of a 
blade-plate electrode filled with a Al2O3 column (εr=9) in the discharge gap. An ICCD camera and 
an electric field diagnosis method called EFISH (Electric field induced second harmonic generation)
were employed, while a two-dimensional fluid model was established for the simulation.
Four discharge types in the PBR were identified based on ICCD images and simulation results, 
including polar discharge at the contact areas, surface streamer along the dielectric column, 
expansion of surface discharge along the dielectric column, and surface ionization waves along the 
dielectric plate. Surface streamers with opposite propagation directions were found, namely forward 
streamer during the pulse rising time and reverse streamer during the pulse falling time. Notably, 
the reverse streamer exhibits a significantly lower velocity compared to the forward streamer.
Both experimental measurements and simulation were conducted to investigate the 
spatiotemporal electric field near the surface of the packing material. The results of both Eexp and 
Esim showed peaks with opposite polarities, and exhibited similar trends. In the simulation, the 
forward streamer head had a higher electric field compared to the reverse streamer head. Moreover, 
during the rest pulse time, the surface electric field was more intense at the contact areas than in 
other regions. The findings of this work provide valuable insights into the discharge mechanism and 
electric field on the catalytic material surface within the PBR.

No abstract