Influence of dielectric materials on discharge characteristics of coaxial DBD driven by nanosecond pulse voltage

The dielectric material is one of the important influencing factors for the dielectric barrier discharge (DBD) characteristics and its application effects. The glass, quartz, polycarbonate (PC), and polytetrafluoroethylene (PTFE) materials are selected as dielectric materials of a coaxial DBD reactor. A nanosecond (ns) pulse power supply is used to drive the coaxial DBD reactors and the influences of dielectric materials on the optical, electrical, and temperature characteristics of DBDs are recorded. The mechanisms of the effects of the dielectric materials on the DBD characteristics are analysed by equivalent electrical model and heat conduct model. From the observation of the discharge, all of the discharges are in the diffuse mode without filament and the coaxial DBD with glass dielectric barrier are more homogenous. With the electrical analysis, it is found that the glass dielectric barrier with larger relative permittivity compared with the other materials leads to a better discharge uniformity and a higher power deposition in gap. At the same applied voltage, the coaxial DBD reactor with glass dielectric barrier also has the highest energy efficiency, which can reach 70.8% at 24 kV peak applied voltage. The operation temperatures of the coaxial DBD reactors after 900 s discharge with different dielectric materials are compared. The coaxial DBD reactor with glass dielectric barrier has the highest outside wall temperature at 78.0 °C. The reactor with PTFE dielectric barrier has the lowest operation temperature at 58.2 °C. With the heat conduct analysis, the results show that the coaxial DBD reactor with glass dielectric barrier has the highest the inner barrier tube temperature at 137.9 °C and has the lowest heat loss power rate at 29.2% under thermal balance. The reported work provides important reference for the selection of dielectric materials for DBD reactors and for the optimization in the industrial application.