Berlin 2008 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 12: Nonlinear dynamics, synchronization and chaos II

DY 12.2: Talk

Tuesday, February 26, 2008, 10:15–10:30, MA 004

Tunable Fermi acceleration in the driven elliptical billiard — •Florian Lenz¹, Fotis K. Diakonos², and Peter Schmelcher^1,3 — ¹Physikalisches Institut, University of Heidelberg, Philosophenweg 12, 69120 Heidelberg, Germany — ²Department of Physics, University of Athens, GR-15771 Athens, Greece — ³Theoretische Chemie, Physikalisch-Chemisches Institut, University of Heidelberg, Im Neuenheimer Feld 229, 69120 Heidelberg, Germany

We explore the dynamical evolution of an ensemble of non-interacting particles propagating freely in an elliptical billiard with harmonically driven boundaries. The existence of Fermi acceleration is shown thereby refuting the established assumption that smoothly driven billiards whose static counterparts are integrable do not exhibit acceleration dynamics. The underlying mechanism based on intermittent phases of laminar and stochastic behavior of the strongly correlated angular momentum and velocity motion is identified and studied with varying parameters. The diffusion process in velocity space is shown to be anomalous and we find that the corresponding characteristic exponent depends monotonically on the breathing amplitude of the billiard boundaries. Thus it is possible to tune the acceleration law in a straightforwardly controllable manner.