Investigation Of The Nanosecond Pulsed Guided Streamer Initiation And Breakdown Using A Ring-To-Plate Configuration

Recently atmospheric pressure pulsed plasma jets (APNPJs) receive great interests due to their applications in various fields including medicine, food processing, bacteria inactivation etc. The generation of repeatable and stable APNPJs is hence important to their efficient applications. Here, we report an experimental study of the streamer initiation and breakdown (i.e streamer to spark transition) of an APNPJ using a ring-to-plate configuration. Using He as the working gas, ~0.26 mm diameter microplasma jet is generated in ambient air when a 0.504 mm outer diameter hollow needle was powered by 200 ns high voltage pulses. The pulsed voltage with respect to the interelectrode gap distance, ranging from 1mm to 11mm, was studied for various pulse width (160 ns – 5 μs), pulse repetition frequency (1 Hz – 10 kHz), and gas flow rates from 35 SCCM to 210 SCCM. While increasing the voltage increases the breakdown probability, longer pulse width and higher repetition rate result in lower hold-off voltage. Moreover, the differences in voltage and current waveforms as well as the UV-visible emissions for the streamer and spark are discussed.