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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. Smolyakov^2)
 
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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