Berlin 2005 – wissenschaftliches Programm

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P: Plasmaphysik

P 7: Poster: Niedertemperaturplasmen / Plasmatechnologie 3, Diagnostik 3

P 7.20: Poster

Freitag, 4. März 2005, 16:30–18:30, Poster HU

Plasma Diagnostics in the Near-Cathode Region of a Free-Burning Arc — •Gerrit Kühn und Manfred Kock — Institut für Atom- & Molekülphysik, Callinstraße 38, 30167 Hannover

Previous measurements[1,2] show strong deviations from the state of local thermodynamical equilibrium (LTE) for the plasma of a free-burning arc (employing argon under atmospheric pressure and currents ranging from 0.5 A to 20 A). Especially in the near-cathode region, the discrepancies are large when the arc is in the so-called blue-core mode, but are also present in the well-known diffuse mode. We report on spatially resolved spectroscopic investigations including the power-interruption technique to obtain the temperature of the electrons as well as of the heavy particles. Applying modern CCD-detector systems and mechanical actuators we reach an improved spatial resolution of about 50 µm, high dynamic ranges of up to 18 bit and short detection timeframes less than 100 ns. We demonstrate that the plasma in the vincinity of the cathode can still be described surprisingly well within a pLTE model.

[1] F. Könemann et.al., J. Phys. D 37 (2004) 171-179

[2] J. Reiche et.al., J. Phys. D 34 (2001) 3177-3184