Dissipation effects in the ratchetlike Fermi acceleration

Abstract

Ac driven asymmetric pulses can be used to control the Fermi acceleration between three different motions, ${\bf A:}$ the {\it accelerated} mode; ${\bf D:}$ the {\it decelerated} mode and ${\bf H:}$ the {\it hyperaccelerated} mode. In this work we show that dissipation strongly affects the particles velocity, reducing the possibility for an accurate control of the dynamics. The saturation time, where the mean velocity starts to be constant due to dissipation, decays with a power law $\sim\gamma^{-\beta}$, where $\gamma$ is the dissipation parameter and $\beta$ is close to 1. The value of the saturated mean velocity also decays with a power law with exponent $\beta\sim0.6$ for the case ${\bf H}$, and $\beta\sim0.3$ for the case ${\bf A}$. In the case ${\bf D}$ this velocity is almost constant for small dissipations.Comment: 5 pages and 4 figs. Accepted in Mathematical Problems in Engineerin