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P: Plasmaphysik

P 15: Diagnostik 2; Niedertemperaturplasmen / Plasmatechnologie 5; Plasma-Wand Wechselwirkung 1

P 15.18: Poster

Tuesday, March 28, 2006, 17:00–19:00, Flure

Transitions from uniform state to regular patterns in DC gas discharge with resistive cathode at low temperature — •Weifeng Shang and Hans-Georg Purwins — Institut für Angewandte Physik, Universität Münster, Corrensstr. 2-4, 48149 Münster

By using a resistive cathode in a planar gas discharge system consisting of a gap of the order of 1 mm filled with Nitrogen or Argon of a few hundred hPa, a uniform discharge covering the whole surface of the cathode can be obtained after the electrical breakdown of the gas. An increase of the current density will destablize the spatially uniform state of the current flow through the gas. Under proper conditions regular patterns, i.e. hexagonal lattice and stripes, can arise out of the uniform background.The specific resistivity of the cathode consisting of a Si(Zn) waffer cooled down to about 130 K can be varied through illumination. The transitions from the uniform state to the patterned state are investigated at various inter-electrode distances between 0.5 mm and 1.5 mm and gas pressures between 50 and 300 hPa. The observed transitions are compared with Turing bifurcations in chemical reaction-diffusion systems.