## 3 Results and Discussion  
### Electrical Characterization  
The plasma discharge was initiated inside the plasma reactor by applying an AC high voltage between 10 and 15 kV on the electrodes. The voltage waveform measured in the plasma discharge at the applied voltage of 14 kV is shown in Figure S2 of the Supplementary Materials.  
The variations of the current waveforms of the plasma discharge as a function of voltage, the rotation frequency of the power electrode, and the gas flow rate are presented in Figure 2. The charge current was due mainly to the formation of instantaneous current shocks between the electrodes for high voltage conditions. These filamentary shocks produced instabilities in the discharge and fluctuation of the current shape. When the applied voltage was increased, the number of shocks increased also, and the discharge current was higher (Figure 2a). As shown in Figure 2b, the detected current also had a high dependence on the frequency of the power electrode. The increment in this frequency resulted in the discharge current rising. The behavior with the gas flow was the opposite  
Figure 1: Scheme of the experimental setup.  
case. A higher gas flow rate produced a reduction in the current, due to the reduction in the current shocks by the increment in the flow rate.  
Figure 3 shows the formation of the filamentary current shocks in the reactor for the stationary power electrode and different rotation frequencies of this electrode. When the rotation frequency increased, the number of shocks was incremented, and the discharge filled the reactor. This fact explains the growth that was observed in the current waveform.  
The average of the consumed power was obtained from the integration of instants power over a period according to the following equation [15]:  
\[P=\frac{1}{T}\int_{0}^{T}IVdt \tag{1}\]  
Table 1 shows the value of the averaged consumed power, \(P\), together with the current in the peak, \(I_{p}\), for the different studied conditions. The maximum variation of the consumed power was with the applied voltage, where \(P\) grew clearly when the applied voltage was increased. As shown, a slighter dependence had the power on the motor revolution frequency. This power decreased for the higher rpm. Finally, the consumed power decreased in the highest flow rate, where the current shocks reduced.  
Figure 3: Photographs of the discharge in the reactor for the stationary power electrode and the rotational frequencies of 9000 and 18,000 rpm at 14 kV applied voltage (photographs for other rotational frequencies are shown in Figure S3 of the Supplementary Materials).  
Figure 2: The current waveforms of the plasma discharge versus (**a**) different voltages applied on the stationary power electrode at 1 sLm gas flow rate, (**b**) rotational frequencies of power electrode at 14 kV applied voltage and 1 sLm gas flow rate, and (**c**) gas flow rates at 14 kV applied voltage and 18,000 rpm rotational frequency of the power electrode.  
When the power electrode started to rotate, the filaments were increased in the plasma discharge and consequently the electrical current was slightly raised. Because of this increase in the electrical current, the consumed power was also changed from 360 W to 375 W. Moreover, the neutral particles passed faster from the electric field zone with the increase in the gas flow rate in the plasma medium. The ionization and thus the production of charged particles in the plasma medium, which affected the electrical current, was decreased. When the current was dropped, the consumed power was also decreased.