Power fluctuations in a driven damped chaotic pendulum

In this paper we investigate the power fluctuations in a driven, dampted pendulum. When the motion of the pendulum is chaotic, the average power supplied by the driving force is equal to the average dissipated power only for an infinite long time period. We measure the fluctuations of the supplied power during a time equal to the period of the driving force. Negative power fluctuations occur and we estimate their probability. In a chaotic state the histogram of the power distribution is broad and continuous although bounded. For a value of the power not too close to the edge of the distribution the Fluctuation Theorem of Gallavotti and Cohen is approximately satisfied.