LAUSR

As a supplement to our previous studies on alternating streamer propagation in mineral oil under bipolar oscillating impulse voltage [Ni et al., Phys. Plasmas 25, 072125 (2018)], this study was conducted to further analyze waveform-dependent 50% breakdown voltages and polarity effects. Contrary to breakdown under unipolar impulses, breakdown voltages under positive bipolar impulses are generally higher than those under negative impulses, except for when the damping factor approaches 1. The polarity effect under bipolar impulses, per alternating streamer propagation in mineral oil, is attributable to the characteristics of positive and negative streamers as well as their roles in the prebreakdown process. The existence of polarity effects under bipolar impulses is also dependent on the arrangement of electrodes.