低气压氮气中放电形式转化的研究

Study on Transition of Discharge in Low Pressure Nitrogen

目前广泛采用介质阻挡放电来获得大面积的均匀放电,但在常压下尤其是在空气中这种放电通常为细丝状放电。为研究在氮气中由均匀放电向柱状放电或丝状放电转化的过渡过程随外加电压变化的规律,实验研究了3.5-20kPa的氮气中,介质阻挡材料分别为聚对苯二甲酸乙二醇酯(PET)和石英的介质阻挡放电现象和电流波形随外加电压的变化情况,研究比较了介质材料对放电现象和特性的影响。研究发现,放电可在低于初始放电电压的情况下维持,并由丝状放电形式向柱状放电形式转化,放电电流和放电面积随之增大。实验结果表明,在低电场下放电会变得更加均匀,可能存在某种由丝状放电向柱状放电过渡的放电形式。但研究未能验证驻极体表面电荷去吸附对放电的影响。

Low temperature plasma has bright future in industry, but it is hard to get glow discharge in atmospheric air due to the lack of the knowledge about mechanism in discharge. Dielectric barrier discharges are widely studied to get homogeneous discharge of large area, however, the dielectric harrier discharge at atmospheric pressure is generally of filamentary mode, especially in air. It has been found that a homogeneous discharge can be obtained in pure nitrogen, and there are some factors responsible for a transition from the homogeneous discharge to a columnar discharge or a filamentary discharge, therefore, the object of this paper is to study mechanisms of the transition of the discharge depending on applied voltages. The current and phenomenon of the dielectric barrier discharge varying with applied voltages are investigated in nitrogen of pressure of 3. 5-20kPa, with the condition of using PET or quartz as the barrier material The amplitude of the applied voltage leading to the discharge is called the critical value. It is found that the discharge is still sustained when the applied voltage is lower than the critical value once the discharge generates, and the discharge transforms from the filamentary mode to a columnar mode with the decrease of the applied voltage. Accompanied with the transition, the discharge current increases and the discharge area becomes large, According to the experimental results, the discharge will be more homogenous when reducing the electric field of the gap, and there could be a transition mechanism controlled the transition from the filamentary discharge to the colurnnar discharge. The discharge phenomenon and the electrical characteristics under different dielectric barrier materials are compared to determine the effect of the harrier material on the discharge, however, it is not approved the affection of the desorption of the surface charge on the discharge.