INFLUENCE OF PULSE WIDTH VARIATION ON THE BREAKDOWN OF PULSED BARRIER DISCHARGES AT ATMOSPHERIC PRESSURE

摘要

Dielectric barrier microdischarges (MDs) with 1 mm gap at atmospheric pressure in nitrogen-oxygen mixtures are investigated. They are powered by unipolar positive high voltage square pulses with variable pulse width. The spatio-temporal emission development of the MD on the rising and falling slope is recorded by streak and iCCD cameras simultaneously, with high temporal resolution. The voltage pulse width is varied from few microseconds down to several hundreds of nanoseconds. Significant changes in the discharge development are observed depending on the pulse width, i.e. the time between the MD at the rising and falling slope. Especially, this is related to the development and propagation of positive as well as negative streamers in the falling slope. We propose that this discharge mechanism variation is caused by the electric field rearrangement due to the different positive ion densities in the gap.