The fast breakdown mechanism and characteristic diagnosis of nanosecond pulse plate–plate dielectric barrier discharge

Abstract In this paper, a short-gated ICCD and a streak camera were employed to investigate the dynamic evolution and the fast breakdown mechanism of dielectric barrier discharge in helium. Both the discharge evolution in nanoseconds and the fast dynamic breakdown process in tens of picoseconds were recorded, and the generation and quenching mechanisms of active species were analyzed using time-resolved spectroscopy. The results show that the discharge propagates backward from the cathode to the anode immediately after breakdown is achieved, and the backward propagation is stronger. There are two main propagation phases of the discharge from the anode to the cathode, both occurring on the nanosecond scale, with two propagation velocities of 2.15 × 10 6 m s −1 and 3.43 × 10 6 m s −1 as measured by the streak camera. The emission spectra of N 2 (C 3 Π u → B 3 Π g , 337.1 nm) and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mrow> <mml:mtext>N</mml:mtext> </mml:mrow> <mml:mrow> <mml:mtext>2</mml:mtext> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> </mml:mrow> </mml:msubsup> </mml:mrow> </mml:math> (B 2 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">Σ</mml:mi> </mml:mrow> </mml:mrow> <mml:mrow> <mml:mtext>u</mml:mtext> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> </mml:mrow> </mml:msubsup> </mml:mrow> </mml:math> → X 2 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">Σ</mml:mi> </mml:mrow> </mml:mrow> <mml:mrow> <mml:mtext>g</mml:mtext> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> </mml:mrow> </mml:msubsup> </mml:mrow> </mml:math> , 391.4 nm) have a shorter rise and longer fall time, but the rise and fall times of He (3 s 3 S → 2 p 3 P, 706.5 nm) are essentially the same. In addition, the addition of about 1% nitrogen to helium produces more Hemet, which further enhances the effect of Penning ionization and thus promotes discharge breakdown.