Discharge dynamics in a cylindrical SDBD prototype reactor under ns-pulsed and sinusoidal AC operation

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We developed a prototype reactor generating surface dielectric barrier discharges (SDBDs) in ambient air, designed for reliable operation while preventing constructive material degradation. It features stainless steel electrodes and quartz dielectric, both detachable to facilitate reproducible fabrication. The grounded electrode is fully immersed into transformer oil, drastically suppressing undesired parasitic discharges. The device efficiently sustains ns-pulsed and AC discharges at 10 kHz, enabling fundamental studies of their electrical characteristics and spatiotemporal dynamics. The mean electric power (P¯DBD) consumed exhibits a dissimilar non-linear increase with the rising peak voltage (Vp) in each case: P¯DBDpulsed≈0.8–2.5 W for ns-pulsed (Vp=7–9 kV) and P¯DBDAC≈0.9–5.3 W for AC (Vp=7–10 kV) operation. Using ICCD imaging, distinct ionization channels are recorded in the rising part of the pulsed voltage being detached from the driven electrode; during the voltage falling part, a glow-like discharge is formed, remaining anchored on the driven electrode. The rising part of the AC voltage is characterized by erratic, elongated ionization channels in a filamentary form, whereas the falling part leads to a glow-like behavior. During the rising and falling parts of the AC voltage, the discharge reaches maximum propagation lengths (Lmax) of ≈12 and ≈7 mm, respectively, while remaining attached to the driven electrode. The corresponding maximum discharge velocities (vmax) are about 5 × 102 and 3 × 102 m/s. For the ns-pulsed operation, Lmax ≈ 5 mm (vmax≈5 × 105 m/s) and Lmax ≈ 3.5 mm (vmax≈1.5 × 105 m/s) during the rising and falling parts of the voltage pulse, respectively. The SDBD dynamics generated with an ns-pulsed voltage are more reproducible than for the AC case, allowing for the use of a 500 times smaller ICCD gate width (2 ns) and a more accurate description of the discharge's spatiotemporal development. This reactor is suitable for performing fundamental studies and understanding key SDBD features for potential applications such as flow control, biomedicine, and agriculture. However, dedicated studies on the impact of the present results in such applications remain beyond the scope of the present work.

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