毛细管共面介质阻挡放电等离子体特性

Plasma Characteristics of Capillary Coplanar Dielectric Barrier Discharge

共面介质阻挡放电(coplanar dielectric barrier discharge,CDBD)因高压电极和接地电极掩埋在绝缘介质中而具有较长的使用寿命和广泛的应用前景。然而,传统CDBD起始电压高、制作较为复杂,这会限制其应用的进一步发展。因此提出了一种新型的毛细管CDBD结构,即用填充铜粉的毛细管作为高/低压电极,并利用两电极间的紧密接触缩短放电气隙以降低起始放电电压。该研究从流光发展过程、光学特性、电学特性以及活性粒子生成角度对毛细管CDBD进行了系统性的研究,并探究了脉冲电压幅值、上升时间、下降时间、峰值平顶宽度、电极直径以及介质的相对介电常数对等离子体特性的影响。结果表明,毛细管CDBD在单次脉冲作用下存在一次放电和二次放电,分别对应电流极性为正和为负的部分。在脉冲上升沿阶段,流光从相邻高/低压毛细管间的“V型”区域底部产生,然后主要沿着高压电极表面爬升并达到最高点。而在脉冲下降沿阶段,流光则主要沿着接地电极表面发展。高的脉冲电压、短的脉冲上升时间和下降时间有利于放电的增强和活性粒子的生成。同时脉冲上升时间的增加还会使得放电均匀性变差,而脉冲峰值平顶宽度的影响则较为有限。相对介电常数的增加能够增强放电强度和降低起始放电电压,而电极直径的增加虽能增加放电面积,但也会使得放电强度变差。

Coplanar dielectric barrier discharge(CDBD)has a longer lifetime and a wide application prospect by having its high voltage and grounded electrodes buried in an insulating dielectric side by side.However,the traditional CDBD requires a relatively high voltage to be ignited and is complicated to manufacture,which may hinder its further development for application.Therefore,a new CDBD device which utilizes capillaries filled with copper powder as electrodes is proposed,and the close contact between the high-voltage and grounded electrodes can shorten the discharge gap to reduce the onset voltage.In this paper,the capillary CDBD are systematically investigated from the perspective of streamer development process,optical properties,electrical characteristics and active particles generation.In addition,the influences of the pulse voltage amplitude,rising edge,falling edge,peak flat top width,electrode diameter and relative permittivity of the dielectric on the plasma characteristics are also involved.The results show that there are two discharge processes of the primary discharge and the secondary discharge under single pulse,which respectively correspond to the positive and negative parts of the current waveform.During the rising edge phase of the pulse,the streamer is generated from the bottom of the"V-shaped"region,which then climbs along the dielectric surface of the high-voltage electrode and finally reaches the highest point.In the falling edge stage,the streamer mainly develops along the dielectric surface of the grounded electrodes.High pulse voltage,short pulse rise time and falling time are found to be beneficial to the enhancement of discharge intensity and the generation of active particles.Besides,the increase of the pulse rise time will pose a negative effect on the discharge uniformity while the influence of the pulse peak flat-top width is relatively limited.The increase of the relative permittivity can enhance the discharge intensity and reduce the initial voltage.Although a larger discharge region can be generated as the rise of electrode diameter,the discharge intensity is compromised.