The pulsed mode of negative DC corona in nitrogen at atmosphere pressure: Comparison with Trichel pulses in air

Abstract

The pulsed mode of negative DC corona discharge in nitrogen at atmosphere pressure is investigated in needle–plate electrodes and compared with Trichel pulses in air. Current/voltage waveforms and time-resolved discharge pictures are recorded experimentally. It is found that the pulsed mode only appears in the presence of a large ballast resistor. The slope of pulsed mode time-averaged voltage–current curve is negative, in contrast to that of Trichel pulses. A transition of slope from negative to positive is tracked by increasing the oxygen fraction. The development of pulse discharge in nitrogen can be divided into three stages: (1) current raising stage, (2) current falling stage, and (3) charging stage. At stage 1, the current raises and forms a peak. The leading edge lasts for dozens of nanoseconds, similar to that of Trichel pulses in air. At stage 2, the voltage decreases monotonically, where a second hump can appear in the current waveform. Through intensified charge coupled device (ICCD) pictures and fluid model simulation, the hump is attributed to the further development of temporal glow discharge. The relative value and occurrence time of this hump are shown to be affected by a parallel capacitor, the space between electrodes, and the applied source voltage. At stage 3, the current remains constant, combined with a rise of gap voltage. Meanwhile, the stray capacitor is charged, which is analyzed by an equivalent circuit model. Through this experiment and simulation, we further clarify the mechanisms of pulses in nitrogen and differences between pulses in nitrogen and Trichel pulses in air.

Review on ionization and quenching mechanisms of Trichel pulse*

“…As Raizer's textbook said, Trichel pulse was observed only in the electronegative gases [1] (such as air and SF 6 [76,77] ), but there have been quite lots of works about the negative DC pulsed mode in various non-electronegative gases. [28,40,[42][43][44][45] Sun et al [44] reported that the current waveforms within 30 ns were the same in both nitrogen and air at atmospheric pressure. A similar trend has been discussed involving the initial stage of the breakdown by Černák et al [40] After comparing the initial stage of the breakdown current under negative DC voltage in nitrogen and the Trichel pulse current in electronegative gases, they found that the leading edge and the initial quenching process are quite similar.…”

“…[1] While with the development of simulations and experiments, more detailed processes have been further investigated. On the other hand, since the pulsed modes in non-electronegative gases [40][41][42][43][44][45] cannot be explained by the impact of negative ion, a lot of researchers have devoted to revealing its mechanisms. In this section, we will review some quenching mechanisms involving pulsed modes in both electronegative and non-electronegative gases respectively.…”

“…[78] Besides the quenching mechanisms caused by the gas itself, some other researchers emphasized the profound role of the external circuit. Sun et al [44] emphasized that in nitrogen the pulsed mode can be realized only with a large ballast resistor (MΩ), which leads the source to not supply charge in time, so the discharge is only fueled by the charge from the stray capacitance. Then the voltage of the stray capacitance, which equals cathode voltage, will drop until the discharge is quenched.…”

“…On the other hand, quenching and regenerating of regular pulses are dominated by negative ions in electronegative gases, which is generally well accepted. [30][31][32][33][34][35][36][37][38] However, the pulsed mode has been reported in non-electronegative gases [40][41][42][43][44][45] which challenges the role of negative ions. In this review, we summarize the pulsed mode in non-electronegative gases (whether this mode can be called as Trichel pulse is still not conclusive) since we can get a comprehensive understanding of quenching mechanism through the comparison.…”

High‐time‐resolution imaging of transient discharge processes without fixed triggering

“…Current imaging equipment has limitations in time resolution and detection sensitivity, resulting in a less precise acquisition of transient optical information. Under DC, researchers usually discuss trends in luminescence morphology and intensity, and the imaging results are not clear enough [1,[13][14][15]. Therefore, the available means are still insufficient to provide quantitative theoretical descriptions.…”