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(TH/2-4) Intermittency and Structures in Drift Wave Turbulence: Towards a Probabilistic Theory of Anomalous Transport

E.J. Kim1), P.H. Diamond1), S. Champeaux1), I. Gruzinov1), O. Gurcan1), C. Holland1), M. Malkov1), M.N. Rosenbluth1), A. Smolyakov2)
1) University of California, San Diego, La Jolla, CA, USA
2) University of Saskatchewan, Saskatoon, Canada

Abstract.  There is now a plethora of evidence from simulation and experiment that plasma turbulence is highly intermittent and turbulent transport has a fundamentally ``bursty'' character. Thus, one is motivated to develop a probabilistic theory of plasma transport, focusing on the probability distribution function (pdf) of flux, rather than anomalous transport coefficients. We present progress towards such a theory of drift-wave turbulence and transport, as well as more general studies of structure formation. Calculation of a pdf for the Reynolds stress in the Hasegawa-Mima system is facilitated via the use of path-integral methods, and found to depart from Gaussian. A simple model of drift-wave packet evolution in the presence of a zonal flow is derived via analogy to self-organized criticality theory. Detailed studies of streamer dynamics indicate that they form easily, and are able to robustly self-saturate. Investigation of ETG turbulence has led to the novel idea of magnetic streamers as possible sources of efficient electron thermal transport. Finally, a simple sandpile model utilizing a bistable cellular automoton rule has provided intriguing insights into barrier formation.

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IAEA 2003