Experimental investigation on cathode layer of surface dielectric barrier discharge plasma by surface potential measurement

The cathode layer of surface dielectric barrier discharge plasma is investigated experimentally by using the surface potential measurement under different bias voltages. Positive charge accumulation is found near the edge of the exposed electrode (x = 0 mm) under negative DC bias voltage. In addition, the plasma electromotive force (EMF) distribution curve near the edge of the exposed electrode diverges with the negative DC bias voltage. These phenomena are in good agreement with the conclusion that the cathode layer shows positive potential in time average. Five actuators with different exposed electrode widths are designed to study the relationship between the cathode layer and the mechanical properties of the actuator. With the widening of the exposed electrode, the positive charges in the cathode layer increase, and the plasma EMF divergence is more pronounced. However, the thrust force decreases. Moreover, the variation of thrust force with DC bias voltage is consistent with the change of the plasma EMF. The experimental results show that the narrow-exposed electrode actuator for the cathode layer with a small size and low number of positive ions has better mechanical properties. By analysis, this is mainly due to the lower number of positive ions of the cathode layer, producing less shielding from the applied voltage. More electrons are emitted from the cathode layer. This paper provides a method for the detection and study of the cathode layer. In addition, it can provide insight into how the cathode layer affects the development of thrust force.