Design and Characterization of a Solid-State Marx Generator for Plasma-Activated Water Generation

Low-temperature plasma generated at atmospheric pressure in contact with water generates highly oxidizing chemical species that are capable of degrading recalcitrant organic contamination. This contribution describes the design and characterization of a unique repetitive pulsed power source and provides a detailed characterization of the generated plasma and plasma-activated liquid, resulting from the interaction between plasma and water. The electrical efficiency of the system was found to range between 37% and 49% depending on the pulse repetition rate in the 5–500 Hz range. Optical emission spectroscopy (OES) was used to determine both the electron density of the plasma and rotational temperature as a function of repetition rate and liquid conductivity, which reached the peak values of 560 K and
$10^{17}$
cm
$^{-3}$
, respectively. All plasma-treated water samples showed a decrease in pH from an initial value of
$\sim $
5.7 to below 4. The oxidation-reduction potential (ORP), nitrite, and nitrate concentration were all found to increase with pulse repetition rate, attributed to an increase in the time-averaged plasma density, yielding more gas-phase reactive species to react at the liquid interface and subsequently form longer lived intermediaries. This study therefore describes the development of an efficient pulsed plasma source for the activation of liquids.