Fermi Accelerator Model Research Articles

Acceleration behaviors of Fermi accelerator model excited by Van der Pol oscillator

In this paper, we investigate on dynamics of a generalized Fermi accelerator model with a moving wall described by a nonlinear Van der Pol oscillator. Different acceleration behaviors appear due to the discontinuity brought by impact and the stationary periodic excitation of the moving wall. Utilizing the theory of discontinuous dynamical systems, acceleration mechanism of the particle is studied and the analytical conditions for stick motion and grazing motion are obtained. By the use of generic mappings between different boundaries including stick and non-stick motions, periodic motions of the Fermi accelerator can be constructed, and corresponding local stability and bifurcations can be discussed according to mapping dynamics. Finally, different acceleration behaviors including periodic, chatter and stick motions are presented and illustrated.

Fermi accelerator: A new insight from quantum theory of motion

Quantum localization is observed in the Fermi accelerator model with monochromatic fluctuation using the Ehrenfest description of quantum dynamics as well as through the quantum theory of motion (QTM). The effects of variations in time period and amplitude of an oscillating wall for a particle in a box, on energy and quantum phase space structures are analyzed. The effects of fluctuation decay with an increase in distance from the fluctuating wall. It is also observed that small amplitude as well as high frequency fluctuation provides enhanced quantum localization. The “quantum phase space structure” in the Ehrenfest description is constructed by following time-dependent Fourier grid Hamiltonian method while that for the grid points are formed from their trajectories obtained from QTM. © 2015 Wiley Periodicals, Inc.

Dynamical properties for a mixed Fermi accelerator model

The behavior of the decay of velocity in a semi-dissipative one-dimensional Fermi accelerator model is considered. Two different kinds of dissipative forces were considered: (i) F∝−v and; (ii) F∝−v2. We prove the decay of velocity is linear for (i) and exponential for (ii). During the decay, the particles move along specific corridors which are constructed by the borders of the stable manifolds of saddle points. These corridors organize themselves in a very complicated way in the phase space leading the basin of attraction of the sinks to be seemingly of fractal type.

One-dimensional Fermi accelerator model with moving wall described by a nonlinear van der Pol oscillator

A modification of the one-dimensional Fermi accelerator model is considered in this work. The dynamics of a classical particle of mass m, confined to bounce elastically between two rigid walls where one is described by a nonlinear van der Pol type oscillator while the other one is fixed, working as a reinjection mechanism of the particle for a next collision, is carefully made by the use of a two-dimensional nonlinear mapping. Two cases are considered: (i) the situation where the particle has mass negligible as compared to the mass of the moving wall and does not affect the motion of it; and (ii) the case where collisions of the particle do affect the movement of the moving wall. For case (i) the phase space is of mixed type leading us to observe a scaling of the average velocity as a function of the parameter (χ) controlling the nonlinearity of the moving wall. For large χ, a diffusion on the velocity is observed leading to the conclusion that Fermi acceleration is taking place. On the other hand, for case (ii), the motion of the moving wall is affected by collisions with the particle. However, due to the properties of the van der Pol oscillator, the moving wall relaxes again to a limit cycle. Such kind of motion absorbs part of the energy of the particle leading to a suppression of the unlimited energy gain as observed in case (i). The phase space shows a set of attractors of different periods whose basin of attraction has a complicated organization.

Non-uniform drag force on the Fermi accelerator model

Some dynamical properties of a particle suffering the action of a generic drag force are obtained for a dissipative Fermi Acceleration model. The dissipation is introduced via a viscous drag force, like a gas, and is assumed to be proportional to a power of the velocity: F∝−vγ. The dynamics is described by a two-dimensional nonlinear area-contracting mapping obtained via the solution of Newton’s second law of motion. We prove analytically that the decay of high energy is given by a continued fraction which recovers the following expressions: (i) linear for γ=1; (ii) exponential for γ=2; and (iii) second-degree polynomial type for γ=1.5. Our results are discussed for both the complete version and the simplified version. The procedure used in the present paper can be extended to many different kinds of system, including a class of billiards problems.

Competition between suppression and production of Fermi acceleration

The behavior of the average velocity for a classical particle in the one-dimensional Fermi accelerator model under sawtooth external force is considered. For elastic collisions, it is known that the average velocity of the particle grows unlimitedly because of the discontinuities of the derivative of the moving wall's position with respect to time. However, and contrary to what was expected to be observed, the introduction of a friction force generated from a slip of a body against a rough surface leads to a boundary separating different regions of the phase space that yields the particle to either experience unlimited energy growth or suppression of Fermi acceleration. The Fermi acceleration is described by using scaling arguments. The formalism presented can be extended to two-dimensional time-dependent billiards as well as to higher-order mappings.

The Feigenbaum's delta for a high dissipative bouncing ball model

We have studied a dissipative version of a one-dimensional Fermi accelerator model. The dynamics of the model is described in terms of a two-dimensional, nonlinear area-contracting map. The dissipation is introduced via inelastic collisions of the particle with the walls and we consider the dynamics in the regime of high dissipation. For such a regime, the model exhibits a route to chaos known as period doubling and we obtain a constant along the bifurcations so called the Feigenbaum's number delta.

A simplified Fermi Accelerator Model under quadratic frictional force

Some dynamical properties for a simplified version of a one-dimensional Fermi Accelerator Model under the action of a small dissipation is studied. The dissipation is introduced via a damping force which is assumed to be proportional to the square particle's velocity. The dynamics of the model is described by using a two-dimensional, nonlinear area contracting mapping for the variables velocity of the particle and time. Our results confirm that the structure of the phase space of the conservative version is replaced by a large number of attracting periodic orbits. For a fixed set of control parameters, we obtain many periodic attractors and show that most of them posses low period. The stable orbits produce a complex structure of basin of attraction whose limit cover almost all phase space, thus suggesting a fractality.

Scaling properties of the regular dynamics for a dissipative bouncing ball model

Some scaling properties of the regular dynamics for a dissipative version of the one-dimensional Fermi accelerator model are studied. The dynamics of the model is given in terms of a two-dimensional nonlinear area contracting map. Our results show that the velocities of saddle fixed points (saddle velocities) can be described using scaling arguments for different values of the control parameter.

A family of crisis in a dissipative Fermi accelerator model

The Fermi accelerator model is studied in the framework of inelastic collisions. The dynamics of this problem is obtained by use of a two-dimensional nonlinear area-contracting map. We consider that the collisions of the particle with both periodically time varying and fixed walls are inelastic. We have shown that the dissipation destroys the mixed phase space structure of the nondissipative case and in special, we have obtained and characterized in this problem a family of two damping coefficients for which a boundary crisis occurs.

Dissipative area-preserving one-dimensional Fermi accelerator model

The influence of dissipation on the simplified Fermi-Ulam accelerator model (SFUM) is investigated. The model is described in terms of a two-dimensional nonlinear mapping obtained from differential equations. It is shown that a dissipative SFUM possesses regions of phase space characterized by the property of area preservation.

A crisis in the dissipative Fermi accelerator model

The dynamics of the full, dissipative, Fermi accelerator model is shown to exhibit crisis events as the damping coefficient is varied. The investigation, based on analysis of a two-dimensional nonlinear map, has also led to a numerical determination of the basin of attraction for its chaotic attractor.

On the dynamical properties of a Fermi accelerator model

In this paper we use discrete dynamical systems formalism to carefully investigate the effect of a time-dependent perturbation on a classical mechanical model. We present a study of a one-dimensional Fermi accelerator model and its parametric dependence on the amplitude of the movement of the wall. We focus on the low-energy region, in which the system may present chaotic behavior illustrated by orbits with stochastic behavior and sensitive dependence on initial conditions. Through numerical analysis, this behavior is quantitatively characterized by a positive Lyapunov exponent and by the position of the boundary of the observed ergodic component. Our results will be analyzed by comparing this model to a simplified version and to the Standard Map. These results indicate that the dynamics of the model is, in a certain sense, very weakly dependent of the parameter.

Dynamical properties of a particle in a classical time-dependent potential well

We study numerically the dynamical behavior of a classical particle inside a box potential that contains a square well which depth varies in time. Two cases of time dependence are investigated: periodic and stochastic. The periodic case is similar to the one-dimensional Fermi accelerator model, in the sense that KAM curves like islands surrounded by an ergodic sea are observed for low energy and invariant spanning curves appear for high energies. The ergodic sea, limited by the first spanning curve, is characterized by a positive Lyapunov exponent. This exponent and the position of the lower spanning curve depend sensitively on the control parameter values. In the stochastic case, the particle can reach unbounded kinetic energies. We obtain the average kinetic energy as function of time and of the iteration number. We also show for both cases that the distributions of the time spent by the particle inside the well and the number of successive reflections have a power law tail.

Quantum localization in one-body dissipation

We show, using the quantum Fermi Accelerator model, that the energy dissipated may saturate in a time of the order of the characteristic period of the mean field oscillation. This localization time increases if the periodicity of the driving field is broken by the addition of a second driving frequency in an irrational ratio with the first. However, energy localization is still present, contrary to standard expectations.

Classical and quantum localization and delocalization in the Fermi accelerator, kicked rotor and two-sided kicked rotor models.

The phenomena of dynamical localization, both classical and quantum, are studied in the Fermi accelerator model. The model consists of two vertical oscillating walls and a ball bouncing between them. The classical localization boundary is calculated in the case of "sinusoidal velocity transfer" [A. J. Lichtenberg and M. A. Lieberman, Regular and Stochastic Motion (Springer-Verlag, Berlin, 1983)] on the basis of the analysis of resonances. In the case of the "sawtooth" wall velocity we show that the quantum localization is determined by the analytical properties of the canonical transformations to the action and angle coordinates of the unperturbed Hamiltonian, while the existence of the classical localization is determined by the number of continuous derivatives of the distance between the walls with respect to time. (c) 1996 American Institute of Physics.

The semiclassical limit of a quantum Fermi accelerator

A classical Fermi accelerator model (FAM) is known to show chaotic behavior. The FAM is defined by a free particle bouncing elastically from two rigid walls, one fixed and the other oscillating periodically in time. The central aim of this paper is to connect the quantum and the classical solutions to the FAM in the semiclassical limit. This goal is accomplished using a finite inverted parametric oscillator (FIPO), confined to a box withfixed walls, as an alternative representation of the FAM. In the FIPO representation, an explicit correspondence between classical and quantum limits is accomplished using a Husimi representation of the quasienergy eigenfunctions.

Exactly solvable models with time-dependent boundary conditions

Exact solutions of three versions of an infinitely deep well with moving boundaries are given. Moreover, a special modification of the quantum analogue of the well-known classical Fermi-accelerator model is proposed and exactly solved. An unlimited particle acceleration suggested by Fermi does not appear within the model. This is in agreement with the recent formal investigations by Seba and Karner.

Quantum chaos in the Fermi-accelerator model.

We study the nature of the quasienergy spectrum of the quantum version of the Fermi-accelerator model consisting of a particle inside a box with one fixed and one oscillating wall.