Comparative study of atmospheric pressure plasma jet characteristics driven by multiple nanosecond pulses with nanosecond intervals and a single nanosecond pulse

Atmospheric pressure plasma jets (APPJs) have gained significant attention across various fields. Modulating the driving voltage waveform has emerged as an effective approach to enhancing control over APPJ characteristics. This study investigates the discharge characteristics of APPJs driven by multiple nanosecond pulses (MNPs) with nanosecond intervals and a single nanosecond pulse (SNP). The effects of helium flow rate and interval between pulses in MNP on the APPJ behavior are analyzed through experiments. The results indicate that APPJs driven by SNP exhibit single-segment propagation, with the length of APPJ increasing slightly as the helium flow rate increases. In contrast, the lengths of APPJs driven by MNPs increase initially and then decreases with increasing helium flow rate. Moreover, shorter intervals between pulses in MNPs lead to a lower critical flow rate at which the APPJ transitions from stable to unstable propagation. MNP-driven APPJs exhibit stepwise propagation behavior, where each subsequent pulse induces a new discharge segment at the end of the preceding discharge channel. The shorter intervals between pulses in MNPs lead to increased conductivity in the discharge channel, facilitating efficient transmission of subsequent pulses to the end of previous discharge channel and enhancing discharge process. These findings underscore the significant role of the interval between pulses and discharge channel dynamics in determining APPJ discharge characteristics. Optimizing the interval between nanosecond pulses driving APPJ holds the potential to enhance its performance in industrial and biomedical applications.