Search for deterministic chaos in ELM time series of ASDEX upgrade Tokamak

Time intervals between edge localized modes (ELMs) from Asdex Upgrade tokamak have been analyzed to determine whether ELM dynamics is chaotic (deterministic) or random (noise-dominated). Both linear and nonlinear prediction methods have been used, Hurst and Lyapunov exponents evaluated, and block entropy analysis performed. No concluding evidence of presence of deterministic chaos has been found. New measurements of significantly longer ELM time series are required to improve the quality of the analysis.