Multichannel discharge modes in atmospheric pressure plasma jet interaction with an offset droplet

Atmospheric pressure plasma jet (APPJ) impinging on an offset droplet is commonly utilized for better uniformity and efficiency for liquid activation purposes. In this Letter, we revealed the significant role of the offset distance between the APPJ axis and droplet center on the discharges, namely, the transition from single discharge to multichannel discharges, and the underlying physical mechanism. The transition phenomena were captured by ns-temporal-resolution imaging and well reproduced by 2D fluid modeling. Furthermore, a derived analytical model highlighted the dominant role of the electric field profile in the formation of multichannel discharges and the competitive interaction with each other. Findings in the present work could benefit the design of a higher-efficiency plasma-activation-liquid reactor.