Evidence of determinism for intermittent convective transport in turbulence processes

In this letter we present evidence that intermittent transport observed in nature, e.g., the scrape off layer of magnetically confined plasma devices, has a strong signature of determinism. We show that the universal distribution of density fluctuation as well as the unique parabolic relation between skewness and kurtosis observed in experimental data can be obtained by a superposition of stochastic and deterministic events. A well known deterministic effect, namely, the loss of transversal stability of periodic orbits embedded in an invariant (inertial) manifold is used to model the spiky nature of the emissions. The intermittent emissions are proposed to be due to local unstable transversal directions of the invariant manifold resulting in an ejection of particles and a consequent burst in the signal. We show that characteristics observed by the emissions namely an impulsive ejection followed by a slow recovery phase can be directly related to the deterministic mechanism proposed.