Three-dimensional pattern in dielectric barrier discharge with modulated gas gap

Abstract

We report a three-dimensional pattern with self-organization in three spatial dimensions in dielectric barrier discharge (DBD) by designing a novel device with modulated gas gap. The distribution of electric field by solving the Poisson equation in the x-y plane varies along the z-axis, and three kinds of gas gaps with different thicknesses have different electric fields. The spatiotemporal dynamics of the pattern is obtained by photomultiplier tubes and intensified charge-coupled device. For estimating the plasma parameters, the emission optical spectra are detected by a spectrograph. In three gas gaps, there are five substructures with different morphologies and plasma states in which two structures discharge at the falling edge of the applied voltage. The variation along the z-axis demonstrates that a three-dimensional pattern is truly obtained. It exhibits some novel phenomena that should advance plasma physics in DBD and pattern dynamics as follows. At the falling edge discharge, the discharge moment of a substructure is dependent upon the polarity of the electrode where the gas gap is close. The variation trend of the molecular vibration temperatures is opposite to that of the electron density whether at the rising or the falling edge of the applied voltage for five substructures. The difference between spatial distribution of the substructure and that of the corresponding electric field indicates the effects of the wall charges. Overall, the formation of the pattern includes the resonance of multiple waves by exciting two pre-set wave vectors at different positions of the z-axis and the self-organization effect caused by the wall charge.