Initial Investigation of the Streamer to Spark Transition in a Hollow-Needle-to-Plate Configuration

Nanosecond pulsed atmospheric pressure plasma jets (ns-APPJs), typically, in the form of guided streamers, are interesting to a broad range of applications including material processing, surface disinfection, and cancer treatment. The generation of repeatable and stable guided streamers depends on the applied voltage pulse, gas condition, and electrode geometry. Guided streamer initiation and breakdown (i.e., streamer to spark transition) are studied here using a needle-to-plate electrode configuration with helium flowing through a hollow needle in ambient air toward a ground plate. The impact of pulse repetition frequency (PRF) and pulsewidth on the breakdown voltage as functions of the gap distance were evaluated. Higher PRFs and longer pulsewidths were found to be associated with lower breakdown voltages for the same gap distance.