Bochum 2015 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 5: Poster Session - Low Temperature Plasmas

P 5.6: Poster

Montag, 2. März 2015, 16:30–18:30, Foyer Audimax

Manipulation of helium barrier discharges by laser surface interaction — •Sebastian Nemschokmichal, Robert Tschiersch, and Jürgen Meichsner — Institute of Physics, University of Greifswald

Barrier discharges are determined by the surface properties of the dielectrics and the deposited surface charges. To study the influence of the surface charges on the discharge, one idea is to release these charges from the dielectric by laser photons and to investigate the change in the subsequent discharge. This is done for a helium barrier discharge operating in the glow-like mode at a gap distance of 3 mm and a pressure of 500 mbar. The actual effect of the laser on the discharge behavior depends strongly on the laser pulse energy. For small laser pulse energies, it is possible to shift the discharge breakdown to earlier times when firing the laser in the pre-phase of the discharge. The laser probably releases only a small amount of electrons from the cathode, but these electrons produce additional ions in the gap and enhance the positive space charge significantly. Increasing the laser pulse energy further, a small laser induced current can be measured or the discharge is even triggered by the laser pulse. This contribution tries to quantify these effects by varying the laser pulse energy, the axial position of the laser in the gap, and the voltage phasing of the laser pulse. The results provide insights in the actual number of released charges from the surface and how they influence the discharge behavior.