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 reports that a simulation of glow discharge in pure helium gas at the pressure of 1.333×103 Pa under a high-voltage nanosecond pulse is performed by using a one-dimensional particle-in-cell Monte Carlo collisions(PIC-MCC) model.Numerical modelling results show that the cathode sheath is much thicker than that of anode during the pulse discharge,and that there exists the phenomenon of field reversal at relative high pressures near the end of the pulse,which results from the cumulative positive charges due to their finite mobility during the cathode sheath expansion.Moreover,electron energy distribution function(EEDF) and ion energy distribution function(IEDF) have been also observed.In the early stage of the pulse,a large amount of electrons can be accelerated above the ionization threshold energy.However,in the second half of the pulse,as the field in bulk plasma decreases and thereafter the reverse field forms due to the excessive charges in cathode sheath,although the plasma density grows,the high energy part of EEDF decreases.It concludes that the large volume non-equilibrium plasmas can be obtained with high-voltagenanosecond pulse discharges.
An experimental investigation of a nanosecond pulsed dielectric barrier dischargein atmospheric air is presented. In the setup a quartz tube was inserted between the cone andplane electrodes in the direction parallel to the electric field. It was shown that the appearanceand property of the discharge were sensitive to the size and the position of the quartz tube.When the tube was placed on the grounded plane electrode, the discharge intensity was found toimprove gradually with the increase in the diameter of the quartz tube. Furthermore, with anappropriate distance between the bottom edge of the quartz tube and the plane electrode, thedischarge tended to exhibit better performance in generating homogeneous diffusive plasma. Thepossible mechanism is discussed.
