Investigation of AC–DC coupled diffuse discharge based on stacked mesh electrodes

Abstract

Non-thermal plasma shows great potential for air purification because of its low temperature, abundant reactive species, and moderate power density. However, in atmospheric-pressure air, the short electron mean free path readily promotes filamentary discharge, leading to the localized distribution of discharge energy and reactive species and thereby reducing purification efficiency. To suppress filamentary discharge and improve air purification efficiency, a diagonally crossed mesh electrode structure was constructed based on microelectrodes, and a wire electrode was introduced to form a combined electrode. On this basis, spatially diffuse plasma was stably generated at a relatively low voltage through AC–DC coupled excitation. First, two mesh electrode structures were constructed using micrometer-scale electrodes, and their electric field distributions were comparatively analyzed by simulation. The results show that the diagonally crossed mesh electrode can form a non-uniform electric field with reduced field non-uniformity, which is beneficial for generating surface diffuse discharge at low voltage. Load characteristics were further analyzed from discharge waveforms, indicating that this structure reduces electrode capacitance and power demand while increasing the proportion of effective discharge area. Second, a wire electrode was placed 5 mm above the diagonally crossed mesh electrode to form the combined electrode. The effects of positive and negative DC electric field distributions on spatial diffuse discharge were comparatively investigated by simulation and experiment. The application of a negative DC voltage to the wire electrode was found to be more conducive to the generation of spatial plasma with good diffusivity. Finally, a multilayer stacked electrode was designed based on the combined electrode structure, and an air purification device was fabricated with an ozone decomposition catalyst. The device exhibited good treatment performance for formaldehyde, TVOC, and fine particulate matter.