Search for low – dimensional chaos in a reversed field pinch plasma

An analysis of experimental data from the RFX (Reversed Field eXperiment) reversed field pinch machine [L.sion Eng. Des. 25, 315 (1995)] is carried out to investigate the possible existence of deterministic chaos in the edge plasma region. The mathematical tools used include Lyapunov exponents, Kaplan–Yorke dimension, minimum embedding dimension estimates and nonlinear forecasting. The whole analysis agrees in ruling out the possibility of low–dimensional chaos: The dimension of the underlying dynamical system is estimated to be > 10. From a critical re–reading of the literature it emerges that the findings of this work are likely to be common to all reversed field pinches.