Negative charge acquisition by isolated single microdroplets from plasma exposure at atmospheric pressure

Abstract Charged liquid microdroplets have generated significant interest recently due to the observation of chemical reaction rate enhancement by orders of magnitude. Droplet charging by plasma irradiation has been observed along with significantly enhanced reaction rates in liquid. In this paper, we measure the charge on fixed size (47 μ m) individual droplets, exposed for approximately 4 ms to a low temperature RF-driven plasma operated at atmospheric pressure. The measured charge values ranged from 2.5 to 3.5 × 10 6 electrons, depending on the droplet trajectory. Results were compared with finite element simulations of plasma charging, which provided estimates of surface electric fields and charge fluxes at the droplet surface and helped advance the development of a theoretical framework for plasma-charged microreactors.