Institute of Applied PhysicsNonlinear Systems and Patternformation  Magnetism  Material Science  Applied Physics 

Highlightssee also Research and Publications. Reduced description of discharge patternsFrom the driftdiffusion discharge model a reactiondiffusion model is derived for planar geometry being capable to describe the selforganized current patterns in a simple yet quantitative manner. Quantitative description of selforganised patterns in a AC gas discharge system with a driftdiffusionsystemFor the first time it is possible to calculate quantitatively experimentally observed selforganised patterns consisting of current filaments in a planar AC gas discharge system operated in glow mode. The used model contains no fitting parameter. Quantitative spatial resolved measurement of surface charges in AC gas discharge systemsWith the help of the electrooptic Pockels effect it was possible to measure with high spatial resolution the surface charge in a running planar AC gas discharge system. This is an important step forward in the characterisation of spatially distributed surface charges that play a fundamental role in dielectric barrier discharges. New mechanism for propagating current filaments in AC gas discharge systemsWith the help of the new mechanism the propagation of filaments in the presence of wet dielectric surfaces can be understood. This is in particular true for the understanding of the experimentally observed path memory effects and related selfavoiding and the stochastic behaviour of trajectories. Optoelectronically controlled biomaterial preparationIn a planar AC gas discharge system with one semiconductor electrode an organic film is exposed to a nitrogen discharge. Areas that were exposed to the discharge are enriched with nitrogen compounds that are known to allow biomaterial, e.g. in the form of cells, to stick to the film surface. Since the discharge can be controlled optoelectronically, this is also true for the distribution of biomaterial. Collective behavior of large ensembles of dissipative solitonsIn the case of selforganized localized structures that are also called dissipative solitons, it was possible to reduce the underlying field equations to ordinary differential equations for quantities like position and velocity. In this way a particle concept is developed, allowing of a simple description of phenomena like active Brownian motion, interaction of dissipative solitons and collective many body phenomena of the latter like compression waves and different states of aggregation. New stochastic data analysis methodBy a new method, for individual localized structures or corresponding manybody systems with stochastic behavior it is possible to extract the intrinsic motion of single objects, the contribution of noise and the interaction laws. In this way, it was possible for the first time e.g. to prove on the basis of experimental data the bifurcation from stationary to intrinsically propagating dissipative solitons in good agreement with theory. Demonstration experimentsA collection of experiments from the areas of Mechanics, Hydrodynamics, Plasma Physics, Electronics and Chemistry demonstrates the evolution of selforganised patterns in spatially extended nonlinear dynamical systems. The observed phenomena are of fundamental importance in nature and in manmade systems, at the same time, they can be understood in a rather simple manner. 
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