大气压空气介质阻挡汤森放电

为了实验研究大气压空气介质阻挡均匀放电的可能性,使用1.5mm以上厚度的Al2O3陶瓷片作为阻挡介质及1～2kHz的高压激励,在大气压3mm空气平板间隙中获得均匀放电。通过ICCD高速摄影得到的放电图像以及电流波形的分析表明这种放电是汤森放电。3mm空气间隙的稳态击穿电压仅约为5.7kV,远低于静态击穿电压11.2kV;还发现了类似氮气DBD汤森放电的"反常熄灭"现象,这两个现象表明陶瓷表面可能存在浅位阱及二次电子发射机制,这对空气汤森放电的起始和维持阶段都至关重要。另外,实验发现陶瓷厚度对空气DBD有重要影响,使用厚度<1.5mm的陶瓷片往往无法避免丝状放电。使用2片厚度各1mm的石英玻璃替代陶瓷片在670Pa～0.1MPa都无法获得均匀放电。上述3mm空气汤森放电的原因归结于陶瓷表面独特的"浅位阱"特性以及阻挡介质限流作用的共同效果。

Townsend Dielectric Barrier Discharge in Atmospheric Pressure Air

In order to experimentally study the possibility of homogenous dielectric barrier discharge(DBD) in atmospheric pressure air as well as its characteristics,the homogenous DBD in 3 mm air gap was obtained at atmospheric pressure,using 1~2 kHz sinusoidal high voltage and no less than 1.5 mm thick alumina as the dielectrics.The discharge was proven as an atmospheric pressure Townsend discharge after analyzing the 10 ns exposure high-speed photographs and the current waveform.The steady breakdown voltage for 3 mm air DBD was calculated to be about 5.7 kV,much lower than 11.2 kV,the static breakdown voltage of 3 mm air gap;Extraordinary extinction was also observed in air just like in nitrogen.Both the two phenomena indicated the existence of the shallow traps and consequently the second-electron emission in the alumina surface,which were important for ignition and maintaining stage of Townsend DBD.It is found that the thickness of alumina is important for air DBD,and the thickness less than 1.5 mm can not avoid the filamentary discharge.If two 1 mm thick quartz plates are used instead of alumina,it is impossible to get homogenous DBD at 670 Pa~0.1 MPa in air.The mechanism of Townsend DBD in 3 mm air gap is attributed to the combined effects of the unique shallow traps in the alumina surface and the current-limitation of the dielectrics.