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

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.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 ...