This paper performs a numerical simulation of concentric-ring discharge structures within the scope of a twodimensional diffusion-drift model at atmospheric pressure between two parallel circular electrodes covered with thin dielectric layers.With a relative high frequency the discharge structures present different appearances of ring structures within different radii in time due to the evolvement of the filaments.The spontaneous electron density distributions help understanding the formation and development of self-organized discharge structures.During a cycle the electron avalanches are triggered by the electric field strengthened by the feeding voltage and the residual charged particles on the barrier surface deposited in the previous discharges.The accumulation of charges is shown to play a dominant role in the generation and annihilation of the discharge structures.Besides,the rings split and unify to bring and annihilate rings which form a new discharge structure.
Effect of airflow on the dielectric barrier discharge in ambient air at atmosphericpressure is presented.The influence of airflow on the spatial distribution and intensity of adischarge were investigated experimentally.A critical frequency of 1 kHz was found.With thefrequency above 1 kHz,when a fast airflow was introduced into the discharge gap,the dischargepatterns varied from filaments to curved stripes and the curvature degree rose with an increasein the airflow speed.At the same time,the discharge intensity decreased.However with thedischarge frequency below 1 kHz,the discharge intensity would get greater with an increase in theairflow speed.
This paper presents the interactions between two cold atmospheric plasma jets.Bychanging the experimental conditions including the gas flow rate,the applied voltage,the powersupply frequency and the inter-electrode distance d,three different interaction modes,attraction,repulsion and combination,were observed.It is shown that the interaction modes of the two jetsare principally affected by the electrodes,the gas flow rate,the plasma jets and the power supplyfrequency.
A one-dimensional fluid model for homogeneous atmospheric pressure barrier discharges in helium is presented by considerilag elementary processes of excitation and ionization including a metastable atom effect. Using this model we investigate the behaviours of the helium metastable atoms in discharges as well as their influence on the discharge characteristics. It is shown that the metastable atoms with a relatively high concentration during the discharge are mainly produced in the active phase of the discharge and dissolved in the off phase. It is also found that the metastable atom collisions can not only provide seed electrons for discharges but also influence the concentration of ions. A reduction of matestable atom density results in a drop in the charged particle densities and causes a qualitative change in the discharge patterns.
