非均匀电场下大气压氦气介质阻挡柱状放电的三种形式和条纹斑图

Three Forms of Columnar Discharge and Stripe Patterns in Irregular-electric-field Atmospheric-pressure Helium Dielectric Barrier Discharge

介质阻挡放电作为方便的低温等离子体源在各领域有广泛应用。柱状放电是氦气介质阻挡辉光放电的常见形式,在特定条件下形成丰富的自组织斑图,其机理尚待研究。为此进行大气压氦气准平行间隙和斜间隙介质阻挡放电实验,拍摄放电图像、测量电压和回路电流波形,研究放电柱演化现象及其机理,并用电场呈梯度连续变化的斜间隙进行验证。准平行间隙柱状放电随外加电压升高有3种形式——起始放电阶段的弥散柱状、过电压阶段的密集柱状和两者转化过程的触手状斑图,两种柱状放电存在跨周期的相互影响。在斜间隙中观察到放电柱定向排列成条纹斑图,其实质为放电柱在多个放电周期中在一定区域内有规律地产生,导致较长曝光时间或肉眼观察下呈现连续的发光条纹。影响放电柱的定向排列的主要因素是间隙中电场的径向分量与法向分量的相对强度。

Dielectric barrier discharge(DBD) is widely used as a convenient low-temperature plasma source. Columnar discharge is a common form of helium dielectric barrier glow discharge, which generates various self-organizing patterns under certain conditions. Consequently, quasi-parallel gap and oblique gap DBD experiments in atmospheric-pressure helium were carried out. Discharge images were taken, voltage and circuit current waveforms were measured, and the evolution phenomenon and mechanism of discharge column were studied. The oblique gap with gradient continuous electric field was designed for verifying the evolution of columnar discharge. The quasi-parallel gap columnar discharge during the increase of applied voltage can be divided into three forms as follows: the diffuse columnar discharge at the initial stage, the dense columnar discharge at the over-voltage stage, and the tentacled pattern in the transition process. The two columnar discharge forms have cross-period interaction. In the oblique gap, the discharge columns can be observed to be arranged in a directional pattern of fringe pattern. The essence of the pattern is that the discharge columns are generated regularly in a certain area in several discharge periods, resulting in a long exposure time or continuous luminous fringe under observation. The main factor affecting the directional arrangement of the discharge column is the relative strength of the radial and normal components of the electric field in the gap.