Effect of ground electrode positioning on plasma dynamics and reactive species generation in a double-ground electrode plasma jet

This study investigates how double ground electrode positioning influences current flow dynamics to enhance reactive oxygen species (ROS) and reactive nitrogen species (RNS) production in a plasma jet. Both ROS and RNS are crucial molecules produced by plasma jets in medicine. We explored the changes in ROS and RNS production by operating a plasma jet with varying spacings between the ground electrodes from 20 to 120 mm. Electrical and optical measurements showed that larger ground electrode spacings facilitated a wider area for charge accumulation along the wall of the dielectric tube, leading to higher electron temperatures. This resulted in a broader ionization region of higher energy, enhancing the dissociation of ambient water vapor molecules and reactivity with the surrounding molecular gases like O2 and N2. Consequently, higher concentrations of H2O2 and NO2− (markers for total ROS and RNS, respectively) were observed in the plasma jet treated water, improving its antibacterial activity. Increased spacing between the ground electrodes augmented the current in the plasma plume. Overall, this study may find use in the future development of plasma jets and for assessing their safety and effectiveness for medical applications.