Max Planck Institute for Dynamics and Self-Organization -- Department for Nonlinear Dynamics and Network Dynamics Group
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Tuesday, 17.01.2006 16 c.t.

Controling chemical turbulence in surface reactions

by Dr. Carsten Beta
from MPI für Dynamik und Selbstorganisation

Contact person: Fred Wolf


Seminarraum Haus 2, 4. Stock (Bunsenstr.)


Spatiotemporally disordered states in catalytic CO oxidation on Pt (110) are characterized by the emergence of topological defects. We analyze the statistical properties of defects in this reaction and derive a probabilistic description based on the gain and loss rates of defects. Deviations from the theoretically predicted rate laws can be explained by short range correlations between defects of opposite topological charge. A global time-delay feedback scheme is implemented experimentally to control chemical turbulence in this reaction. We present results showing that turbulence can be efficiently suppressed and a variety of new patterns can be stabilized by applying a global delayed feedback scheme. We furthermore consider a complex Ginzburg–Landau equation in the Benjamin–Feir unstable regime and analytically investigate the stability of uniform oscillations depending on the feedback parameters. We show that, in agreement with the experiment, a noninvasive stabilization of uniform oscillations is not possible in this type of system.

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