Periodic compression of an adiabatic gas: Intermittency enhanced Fermi acceleration

TL;DR

This paper investigates how periodic compression affects the acceleration of particles in a pulsating scatterer lattice, revealing enhanced velocity growth and non-universal distributions due to intermittency.

Contribution

It introduces a detailed analysis of Fermi acceleration in both finite and infinite horizon regimes, highlighting the role of intermittency in velocity growth.

Findings

Finite horizon case exhibits universal v ~ t velocity scaling.

Infinite horizon case shows enhanced v ~ t ln t growth.

Intermittency leads to non-universal velocity distributions.

Abstract

A gas of noninteracting particles diffuses in a lattice of pulsating scatterers. In the finite horizon case with bounded distance between collisions and strongly chaotic dynamics, the velocity growth (Fermi acceleration) is well described by a master equation, leading to an asymptotic universal non-Maxwellian velocity distribution scaling as v ~ t. The infinite horizon case has intermittent dynamics which enhances the acceleration, leading to v ~ t ln t and a non-universal distribution.