Recurrence in plasma edge turbulence

Common statistics of turbulent electrostatic fluctuations observed at the p lasma edge and scrape-off layer are analyzed in three tokamak devices that have different configurations. The statistics of experimental data collecte d using fixed sampling time is the same than the statistics of the time for which the oscillation return to a specified reference interval of values. This observation, in addition to the finding of power-scaling laws for some average quantities with respect to either the sampling time or the size of the reference interval, suggests that turbulence on tokamaks have recurren t characteristics, typical of a recurrent chaotic low-dimensional system. F urthermore, the first Poincare recurrence time and other dynamical tools ar e used to simulate the mentioned fluctuation statistical properties. (C) 20 01 American Institute of Physics.