## 3 Results and Discussion
### Electrical Characteristics at a High Flow Rates  
In addition to the evaluation of multi-gas plasma generation, the electrical characteristics of the ten-layer DBD plasma were also investigated because energy consumption is a critical consideration in industrial applications. Figure 6a,b show the typical voltage and current waveforms and the Lissajous figure (i.e., Q-U characteristics) in the ten-layer DBD reactor during plasma discharge, where the applied voltage and working gas were set to 22 kV and air, respectively. As shown in Figure 6a, pulse current lines occur simultaneously with the ionization of the working gas when the applied voltage rises above a threshold  
Figure 5: (**a**) Generation of plasma with multiple gases (air, Ar, He, N\({}_{2}\), O\({}_{2}\), and CO\({}_{2}\)); (**b**) air plasma ignited at a high flow rate of 1000 L/min. (>16 kV in the ten-layer DBD reactor). The discharge frequency was dominated by that of the applied voltage, which was 50 Hz. Figure 6b presents the Q-U characteristics of the ten-layer DBD reactor, through which the power dissipated in the discharge was calculated. For example, when the applied voltage was fixed at 22 kV, the discharge power was 98 W at 50 L/min, 96 W at 110 L/min, and 85 W at 1000 L/min, respectively. In addition, the discharge power of the ten-layer DBD reactor (95.50 W at 110 L/min, 22 kV) is approximately 2.32 times larger than that of the two-layer DBD reactor (41.23 W at 110 L/min, 21.5 kV) as studied previously, which can be attributed to the larger discharge space of the ten-layer case (400 cm\({}^{3}\)), which is 2.22 times larger than that of the two-layer case (180 cm\({}^{3}\)); This is in good agreement with the power characteristics of two previously reported high-flow-rate DBD reactors [29]. A plot of the discharge power versus applied voltage is depicted in Figure 6c for the ten-layer DBD reactor, where the working gas was set to air, and the gas flow rate was varied from 50 to 1000 L/min. The discharge power of the ten-layer DBD reactor increased as the applied voltage increased, irrespective of changes in the gas flow rate. For example, at a flow rate of 1000 L/min, as the applied voltage increased from 16 kV to 22 kV, the discharge power rose from 31 W to 85 W. This indicated that the applied voltage played a beneficial role in determining the discharge power (\(P\)) since the discharge power is proportional to the maximum charge (\(q_{max}\)) transferred through and the effective breakdown voltage (\(V_{b}\)) across the discharge gap (i.e., \(P=2\times V_{b}\times q_{max}\times f\), where \(f\) denotes the frequency of the AC power source; \(q_{max}=2C_{d}(V_{max}-V_{b})-2C_{g}V_{b}\), where \(C_{d}\), \(C_{g}\), and \(V_{max}\) represent the total dielectric capacitance, the gap capacitance, and the maximum of the applied voltage, respectively) [45; 49; 50]. On the other hand, a decrease in  
Figure 6: (**a**) Typical voltage and current waveforms and (**b**) Q–U Lissajous figures of the ten-layer DBD reactor at 22 kV; (**c**) power consumption as a function of applied voltage at different gas flow rates (air); and (**d**) plot of capacitances during plasma discharge versus flow rate for the ten-layer DBD reactor. the discharge power was observed at higher gas flow rates (245-1000 L/min), as shown in Figure 6c. This result can be ascribed to the increased airflow, which minimizes the thermal effect caused by the plasma discharge, resulting in a lower relative permittivity of the dielectrics (\(C_{d}\)) used in the ten-layer DBD reactor. The lower the relative permittivity of the dielectrics, the lower the maximum charge (\(q_{max}\)) transferred through the discharge gap for the same applied voltage, resulting in a low discharge power [26; 50].