Dresden 2009 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 3: Nonlinear dynamics, synchronization and chaos I
DY 3.3: Vortrag
Montag, 23. März 2009, 11:30–11:45, ZEU 118
Evolutionary phase space and its impact on Fermi acceleration in the driven elliptical billiard — •Florian Lenz1, Christoph Petri1, Florian N. R. Koch1, Fotis K. Diakonos2, and Peter Schmelcher1,3 — 1Physikalisches Institut, Universität Heidelberg, Philosophenweg 12, 69120 Heidelberg, Germany — 2Department of Physics, University of Athens, GR-15771 Athens, Greece — 3Theoretische Chemie, Physikalisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 229, 69120 Heidelberg, Germany
We perform the first long-time exploration of the classical dynamics of a driven billiard with a four dimensional phase space. The latter is shown to evolve with increasing velocity of the ensemble from a large chaotic sea with a rich structures of stickiness due to regular islands to a phase space consisting of thin velocity channels of diffusive motion that allow for acceleration and are bounded in the three remaining dimensions by large regular regions. As a surprising consequence, we encounter a crossover from amplitude dependent tunable subdiffusion to universal normal diffusion in momentum space. This crossover is traced back to the mentioned change of the structural composition of phase space with varying velocity. Since with increasing collision number an ensemble of particles accelerates, it effectively “sees” an evolutionary phase space which we analyze and understand in depth.