ENHANCEMENT OF LYAPUNOV EXPONENTS IN ONE-DIMENSIONAL, RANDOMLY PHASEDWAVES

For a particle moving in the electric field of many, randomly phase wa ves, numerical measurements show that the Lyapunov exponent (1) asympt otes to a value of 0.4 times the resonance broadening frequency, in co ntrast with previous calculations, and (2) has a peak at intermediate values of the overlap parameter. This latter result indicates that the previously observed enhancement of the diffusion coefficient is not d ue to coherence effects near stable regions of phase space. These resu lts provide further evidence that the standard model is an inadequate description of the turbulent electric field.