Electric field vector measurements in a surface ionization wave discharge

Abstract

This work presents the results of time-resolved electric field vector measurements in a short pulse duration (60 ns full width at half maximum), surface ionization wave discharge in hydrogen using a picosecond four-wave mixing technique. Electric field vector components are measured separately, using pump and Stokes beams linearly polarized in the horizontal and vertical planes, and a polarizer placed in front of the infrared detector. The time-resolved electric field vector is measured at three different locations across the discharge gap, and for three different heights above the alumina ceramic dielectric surface, ~100, 600, and 1100 μm (total of nine different locations). The results show that after breakdown, the discharge develops as an ionization wave propagating along the dielectric surface at an average speed of 1 mm ns −1. The surface ionization wave forms near the high voltage electrode, close to the dielectric surface (~100 μm). The wave front is characterized by significant overshoot of both vertical and horizontal electric field vector components. Behind the wave front, the vertical field component is rapidly reduced. As the wave propagates along the dielectric surface, it also extends further away from the dielectric surface, up to ~1 mm near the grounded electrode. The horizontal field component behind the wave front remains quite significant, to sustain the electron current toward the high voltage electrode. After the wave reaches the grounded electrode, the horizontal field component experiences a secondary rise in the quasi-dc discharge, where it sustains the current along the near-surface plasma sheet. The measurement results indicate presence of a cathode layer formed near the grounded electrode with significant cathode voltage fall, ≈3 kV, due to high current density in the discharge. The peak reduced electric field in the surface ionization wave is 85-95 Td, consistent with dc breakdown field estimated from the Paschen curve for hydrogen. The present set of data on electric field distribution in a surface ionization wave discharge provides an experimental reference for validation of kinetic models and assessing their predictive capability.

Mode Transition of Filaments in Packed-Bed Dielectric Barrier Discharges

“…This trend is in good agreement with recent experimental observations by fast-camera imaging for numerous packing beads with dielectric constant of 25. Once the SIWs are initiated in the PB-DBD, we calculate a propagation speed of the SIWs around 10 6 m/s, which is in the same order as in literature (∼5 × 10 5 and ∼10 6 m/s) [22,23]. The reactive species are highly concentrated on the surface due to the presence of SIWs along the catalyst surface, which agrees with experimental observations in literature [22,36].…”

“…[22,23,29,36]. For −10 kV, the average speed of the volume streamer is 3 × 10 5 m/s, which is in the same order as in Refs.…”

“…SIW discharges operating in N 2 at low pressure (5-100 Torr) and created by high voltage (10-15 kV) nanosecond pulses, traveling along a dielectric surface or a liquid surface, have been experimentally investigated by Intensified Charge Coupled Device (ICCD) camera images [22], with measured propagation speeds of ∼5 × 10 5 m/s. Furthermore, a SIW discharge in hydrogen was experimentally reported, by measuring the time-resolved electric field at special positions, within tens of nanosecond pulse scales, using a picosecond four-wave mixing technique [23]. The results showed that the discharge developed itself as a SIW propagating along the dielectric surface at an average speed of ∼10 6 m/s with a maximum electric field of ∼2.3 × 10 6 V/m [23].…”

“…Furthermore, a SIW discharge in hydrogen was experimentally reported, by measuring the time-resolved electric field at special positions, within tens of nanosecond pulse scales, using a picosecond four-wave mixing technique [23]. The results showed that the discharge developed itself as a SIW propagating along the dielectric surface at an average speed of ∼10 6 m/s with a maximum electric field of ∼2.3 × 10 6 V/m [23].…”

Species-Independent Femtosecond Localized Electric Field Measurement

“…While permitting very precise electric field measurements to as low as a few volts per cm, the method is highly species dependent, requires narrow linewidth lasers tuned to resonant transitions, and is limited to low pressures (~1 Torr) where the Stark effect is apparent over any pressure broadening effects. For non-intrusive electric field measurements at higher pressures, recent papers [4,5] have reported on the measurement of the electric field through a resonant four wave mixing process similar to Coherent Anti-Stokes Raman Scattering (CARS), where two driving lasers operate with wavelengths separated by the vibrational Raman shift of a gas molecule, and the applied electric field enables an otherwise forbidden coherent infrared transition, producing an output infrared laser beam. This approach can also be modeled as a four wave mixing process with one field being the applied field to be measured.…”