Effects of humidity on the dynamics and electron recombination of a pin-to-pin discharge in He+H₂O at atmospheric pressure

Abstract Control of the plasma chemistry is essential for effectiveness atmospheric pressure plasmas in many applications. For this, effects humidity feed gas on discharge need to be considered. Detailed studies are scarce and them dominated by surface interactions, obscuring any volume effects. Here, a negative nanosecond pulsed generated pin–pin 3 mm gap geometry He + H 2 O that enables study kinetics due minimal area. The effect development, electric field electron density investigated through experiments modelling. It found presence water vapour affects both at start pulse (remaining from previous pulse) ionisation rates during ignition phase, leading complex dependence development speed depending concentration. decay studied using 0D global model GlobalKin. dominant reactions responsible concentration determined comparing experimental simulated results these grouped simplified kinetic models. with concentrations increasing 0 2500 ppm, complexity increases particular , clusters becoming important high concentrations. This work also provides data validation models controlled environments.