Microphysics of charge-transfer at plasma walls, Dr. Franz Bronold (Univ. Greifswald)

28.04.2015 von 17:00 bis 18:00

Gastgeber: Dr. Greiner

Low-temperature gas discharges interact with solids which either serve as electrodes connecting the gas discharge to the external circuitry or as walls confining the plasma in space. The most fundamental manifestation of the plasma-solid interaction is the plasma sheath, an electron depleted region adjacent to an unbiased macroscopic object in contact with an ionized gas. It is the positively charged part of an electric double layer whose negatively charged part is inside the wall. In my talk I will discuss the charge-transfer responsible for sheath formation from a firm interface-physics point of view. The first part of the talk will be concerned with the accumulation of very low energy electrons, having kinetic energies below 10 eV, by dielectric walls. In particular, I will show how an invariant embedding approach can be used to calculate the electron sticking coefficient which is of central importance for the modeling of dielectric barrier discharges, dusty plasmas, as well as electric probes. In the second part of the talk I will address electron extraction by charge-transferring atom-surface collisions. Here I will show how quantities of interest for plasma physicists, wall recombination and secondary electron emission coefficients, can be obtained from a non-equilibrium quantum-impurity model. Besides wall parameters the microscopic modeling of sheath formation suggests new vistas for plasma diagnostics and manipulation. With this partly speculative look into the future I will close the talk.

Der Vortrag findet um 17:00 Uhr im Hans Geiger Hörsaal (LS 13 / R. 52) des Physikzentrums statt. Ab 16.45 werden Kaffee und Gebäck angeboten. Kaffeebecher sind mitzubringen!

Alle an neuen physikalischen Fragestellungen Interessierte sind herzlich eingeladen, insbesondere Studierende.

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