Study on OH Radical Production Depending on the Pulse Characteristics in an Atmospheric-Pressure Nanosecond-Pulsed Plasma Jet

Hydroxyl radicals (OH) play a crucial role in plasma-bio applications. As pulsed plasma operation is preferred, and even expanded to the nanosecond range, it is essential to study the relationship between OH radical production and pulse characteristics. In this study, we use optical emission spectroscopy to investigate OH radical production with nanosecond pulse characteristics. The experimental results reveal that longer pulses generate more OH radicals. To confirm the effect of pulse properties on OH radical generation, we conduct computational chemical simulations, focusing on two types of pulse properties: pulse instant power and pulse width. The simulation results show that, similar to the experimental results, longer pulses generate more OH radicals. In the nanosecond range, reaction time is critical for OH radical generation. In terms of chemical aspects, N-2 metastable species mainly contribute to OH radical generation. It is a unique behavior observed in nanosecond range pulsed operation. Furthermore, humidity can turn over the tendency of OH radical production in nanosecond pulses. In a humid condition, shorter pulses are advantageous for generating OH radicals. Electrons play key roles in this condition and high instant power contributes to them.

Automated summary

In this study, the relationship between OH radical production and nanosecond pulse characteristics was investigated using optical emission spectroscopy. The results showed that longer pulses generated more OH radicals, which was confirmed by computational chemical simulations. The simulations also revealed that reaction time and N-2 metastable species played critical roles in OH radical generation in the nanosecond range. Additionally, humidity was found to affect the tendency of OH radical production, with shorter pulses being more advantageous in humid conditions.