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

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.