Characteristics of Shallow Traps in the Dielectric Surface and Their Effects on Diffuse Dielectric Barrier Discharge in Air

摘要

Diffuse Townsend dielectric barrier discharge (DBD) was realized in 3-mm air gap at atmospheric pressure using special Guangdong Zhuhai Yueke Tsinghua Electronic Ceramics Company, Ltd (GTT) ceramics as the dielectric while discharges with dielectric of other ceramics or quartz were always filamentary. It is supposed that there exist shallow traps ( E<1 eV) in dielectric surface. In order to experimentally study how the shallow traps influence the generation of diffuse DBD in air and to explore the mechanism of extraordinary extinguishment in Townsend DBD, thermally stimulated current measurements were performed. It was found the trap level of two types of ceramics was 0.34–0.36 eV, lower than 0.61 eV of quartz, which made it more easily to desorb trapped electrons for the ceramics. There was 280.8 nC of trap charge in GTT ceramics, which was much more than that in common ceramics (38.3 nC) and quartz (15.12 nC). Pulse electroacoustic measurement also indicated that GTT ceramics could acquire more seeds electrons with a longer decay time than the other two dielectrics. Scanning electron microscope observations clearly demonstrated denser distribution and better dispersion of grains in GTT ceramics surface, as was supposed to be the reason why it behaved better than other dielectrics. The results prove that there exist shallow traps in dielectric surface, which could offer seed electrons for generation of diffuse DBD. Lower trapping energy and higher density in the material would make it more easily to generate diffuse DBD.