Coupled Sliding Discharges: A Scalable Nonthermal Plasma System Utilizing Positive and Negative Streamers on Opposite Sides of a Dielectric Layer

Statement of Significance

 Placing strip electrodes on opposite sides of a dielectric layer, but with anodes and cathodes being reversed, as shown in the figures, allowed us to generate positive and negative streamer discharges simultaneously on opposite sides of the dielectric. With applied voltage pulses of approximately 100 ns, the voltages which were required to generate these discharges were about 5 kV lower than those generally required for negative streamer discharges. The low voltage operation and the reproducibility of these discharges are assumed to be due to the coupling of the two types of discharges through their positive and negative surface charges. This coupling allows the stacking of such electrode systems and therefore the fabrication of compact reactors with multiple positive and negative streamer discharges in parallel. Experiments on the use of these discharges in chemical reactors, focusing on ozone synthesis and nitric oxide conversion from air showed a similar or better efficiency as that of positive streamer reactors.       

Coupled Sliding Discharges: A Scalable Nonthermal Plasma System Utilizing Positive and Negative Streamers on Opposite Sides of a Dielectric Layer

Plasma Chemistry and Plasma Processing, July 2014, Volume 34, Issue 4, pp 871-886.

Muhammad Arif Malik, Chunqi Jiang, Shirshak K. Dhali, Richard Heller, Karl H. Schoenbach.

 

  1. Frank Reidy Research Center for Bioelectrics, Old Dominion University, 4211 Monarch Way, Suite 300, Norfolk, VA, 23508, USA.
  2. Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, VA, 23529, USA.

Abstract

 

A nonthermal plasma system based on simultaneously formed positive and negative streamers on either side of a dielectric layer is described. The coupled sliding discharge (CSD) reactor based on this concept was found to be scalable by stacking and operating multiple electrode assemblies in parallel, similarly to the shielded sliding discharge (SSD) reactor reported earlier. A comparison of the two systems showed that although the energy density in the CSD reactor was lower, the efficiency for NO conversion and ozone synthesis from dry air were significantly higher. The energy cost for 50 % NO removal was ~30 eV/molecule compared to ~60 eV/molecule in the case of the SSD under the same conditions of 330 ppm initial NO concentration in air. The energy cost decreased to ~12 eV/molecule in both cases when NO was mixed with plasma-activated air at the outlet of the reactor to utilize ozone for NO conversion i.e., indirect plasma treatment. The energy yield for ozone generation from dry air was at ~70 g/kWh, comparable in both systems. The results show that the concept of a CSD, as that of SSDs, allows the construction of compact, efficient plasma reactors.

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