Hydrodynamic effects induced by nanosecond repetitive pulsed discharges

Abstract

The intense energy released in a burst of nanosecond sparks is shown to induce hydrodynamic effects over large spatial scales of the order of a centimeter. This gas motion transports the active species produced by the discharge into the surrounding space. The present work is dedicated to the detailed measurements of the energy deposited in plasma and its redistribution in space through hydrodynamic degrees of freedom.

Excitation and relaxation of the asymmetric stretch mode of CO2 in a pulsed glow discharge

“…More specifically, the most efficient reduction channel is considered to be the uppumping of the asymmetric stretch vibration toward the dissociation limit, resulting in only a little excess energy in the form of heat [1][2][3]. Over the recent years, researchers have studied this topic extensively [4], both numerically [5][6][7][8][9][10][11][12][13] and experimentally [14][15][16][17][18][19][20][21][22][23][24][25][26], often including the CO 2 vibrations in the discussion.…”

Jetting axial flow induced by nanosecond repetitively pulsed discharges in quiescent ambient air

“…It can be seen, that even though T max e is higher for higher initial T gas or E/N values, this does not have any substantial effect on the maximum value of power density. The latter is mostly defined by the electron number density, which increases from 10 16 to ∼10 19 cm −3 between 12 and 14 ns, as shown in figure 16(a).…”

“…Polarity effect. The hydrodynamic effect produced by a single-shot nanosecond spark discharge was recently studied in [16,17,19,20]. It was shown in [17] that a toroidal gas recirculation pattern may occur around the discharge channel after a single nanosecond spark.…”

“…Due to the fast heat release, the nanosecond spark discharges produce intense hydrodynamic distortions. The hydrodynamic effects of NRPD have been extensively studied in a single-shot regime in a quiescent environment both experimentally [11][12][13][14][15][16][17] and numerically [18,19]. In particular, it was shown in [15] that fast gas heating on a nanosecond time scale leads to the formation of a cylindrical shock wave after discharge initiation.…”

“…It was shown that the intensity of the shock wave significantly depends on the energy fraction spent on fast gas heating which is dictated by reduced electric field values. In [11,16,17] it was shown that a toroidal recirculation pattern is formed within a few tens of microseconds around the gap axis. Stepanyan et al [17] showed that the appearance of a torus occurs only above a certain threshold of the deposited energy density.…”