The discharge mode differences of positive DC corona between silicon and tungsten needles for electrostatic elimination application

Abstract

This paper investigates the discharge mode differences between non-metallic and metallic needles in the field of electrostatic elimination. An experimental measurement system for needle-plate gap discharge under positive DC voltage is established, and it particularly focuses on discharge characteristics of silicon and tungsten needles with distinct curvature radii. Attributes including pulse repetition frequency, waveform parameters and pulse uniformity in different regimes were investigated quantitatively. Experimental results reveal that, three successive regimes of silicon needle discharge can be observed, including streamer corona, glow discharge, and spark breakdown. Tungsten needle exhibits a sequential transition of streamer corona, filamentary discharge, brush, and spark breakdown. And the streamer corona regime can be further delineated into spontaneous streamer, periodic streamer, and cluster streamer. Additionally, the effect of needle curvature radius on discharge parameters is also obtained. Needles with smaller curvature radius is easier to acquire pulses with high repetition frequency, while the needle with larger curvature radius is more likely to obtain pulses with high amplitude. The disparities in the discharge regimes between silicon needles and tungsten needles can be attributed to the variations in their conductivity properties and the different ways of charge migration and dissipation induced by the spatial electric field. And the discharge needle for electrostatic elimination is recommended to work in the periodic discharge stage with good uniformity and stability.