Atomic Oxygen Maximization in High-Voltage Pulsed Cold Atmospheric Plasma Jets

This paper presents a new device generating high-voltage pulsed cold atmospheric plasma jets. With these plasmas, the quantity of atomic oxygen (and, accordingly, the chemical activity) is a lot higher than that in previous researches. The main characteristic of the new device is the usage of three tubular needle-type electrodes connected in parallel. By applying high-voltage pulses (with 20-30-kV amplitude, duration of hundreds of nanoseconds, and hundreds of pulses per second), three independent discharges are formed in the discharge room. The plasma-forming gas is He, with a low quantity of oxygen introduced through the high-voltage electrodes. Each discharge has an optimal percentage of 0.5 % vol. O₂ in He, which maximizes the quantity of atomic oxygen in the plasma. The plasmas of the three discharges unite to a single jet though, which contains a quantity of atomic oxygen that is a lot higher than that of the plasma of each discharge. The emission spectra of the plasma jets show the maximization of the intensity of the O I 777 nm line when a concentration of 1.5% vol. O₂ in He (three times higher than so far) is introduced in the plasma-forming gas.