The effect of laser light interaction with alumina surface of a single filament coplanar dielectric barrier discharge has been investigated. It has been found that for laser photon energy lower than the pure alumina photoelectron emission threshold, the laser beam was effective in triggering single streamer discharge below regular ignition voltage threshold. This work demonstrates that triggering of the filamentary discharge occurs due to the laser induced extraction of electrons originally trapped by the plasma radiation at the dielectric surface; the trap energy levels lower than the dielectric band gap explain the easier electron detrapping due to incident laser photons.
In this study, the charge trapping effect in alumina dielectric surfaces has been deeply investigated by means of a dedicated dielectric barrier discharge apparatus in different discharge regimes and gas mixtures. This work further validates our previous findings in the case of air discharges in a filamentary regime. Long lasting charge trapping has been evidenced by ex situ thermoluminescence characterizations of alumina dielectric barrier plates exposed to a plasma. The density of trapped surface charges was found to be higher in the glow discharge with respect to pseudo-glow and filamentary regimes, and for all regimes the minimum trap activation temperature was 390 K and the trap energy was less than or around 1 eV. This implies that in the case of glow discharges a higher reservoir of electrons is present. Also, the effect was found to persist for several days after running the discharge.
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