Behavioral characteristics of nanosecond pulsed discharge in coaxial electrodes

Abstract

The environmental improvements by pulsed discharge plasma, a type of nonthermal plasma, have received much attention all over the world. The observation of discharge plasmas is beneficial for better understanding of the plasma physics of this growing field. Recently, nanosecond (ns) pulsed discharge with a short pulse duration of 5 ns achieved the higher energy efficiency on ozone generation and NO removal. However, the underlying mechanisms of these high efficiencies remain unclear. In the present study, the effects of electrode geometry on propagation process of ns pulsed discharge in coaxial electrodes were investigated using an ICCD camera. As the results, increasing wire diameters from 0.2 to 2.0 mm lead the different streamer discharge parameters; propagation velocity of streamer heads from 4.8 mm/ns to 12.5 mm/ns, peak of discharge current from 243 to 328 A, respectively. Therefore, it is concluded that the wire diameter is one of the paramount parameters to control the characteristics of the ns pulsed streamer discharge.

Nanosecond pulsed streamer discharges: II. Physics, discharge characterization and plasma processing

“…A similar mechanism was reported in [69]. Table 7 shows the streamer onset characteristics in different N 2 /O 2 gas compositions [67]. The average propagation velocity of the streamer heads under N 2 /O 2 mixed gases was faster than that of pure N 2 .…”

“…In other plasma processing applications, air is a common gas because the target gas often includes ambient air. Here, the influence of nitrogen and oxygen gas composition ratios on nanosecond pulsed discharge behavior was investigated using 5 ns pulse voltage [67]. To investigate the effects of nitrogen/oxygen ratio, six different N 2 and O 2 ratios were used: 0, 20, 40, 60, 80, and 100% O 2 versus the complementary N 2 percentage.…”

“…Streamer onset characteristics in different N 2 /O 2 gas compositions (5 ns pulse discharge). Reproduced with permission from[67].…”

Influence of voltage and gap distance on the dynamics of the ionization front, plasma dots, produced by nanosecond pulsed discharges at water surface

“…This behavior suggests some links with the propagation velocity of the ionization front. Several studies addressed the propagation of discharges at the surface of dielectric materials, including liquids [22][23][24][25][26][27][28]. In this context, one of the fundamental phenomena is the transition from axial (across the gap) to radial propagation (at the dielectric surface).…”

“…In this context, one of the fundamental phenomena is the transition from axial (across the gap) to radial propagation (at the dielectric surface). This phenomenon was explained by two features: (i) significant reduction of photoionization, as the streamer's head approaches the dielectric surface, and (ii) charge accumulation at the liquid surface that produces a strong field capable of initiating avalanches, followed by streamers at the surface [22].…”