The momentum flux probability distribution function for ion-temperature-gradient turbulence
- University of Sheffield, Department of Applied Mathematics, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom)
There has been overwhelming evidence that coherent structures play a critical role in determining the overall transport in a variety of systems. We compute the probability distribution function (PDF) tails of momentum flux and heat flux in ion-temperature-gradient turbulence, by taking into account the interaction among modons, which are assumed to be coherent structures responsible for bursty and intermittent events, contributing to the PDF tails. The tail of PDF of momentum flux R=<v{sub x}v{sub y}> is shown to be exponential with the form exp(-{xi}R{sup 3/2}), which is broader than a Gaussian, similar to what was found in the previous local studies. An analogous expression with the same functional dependence is found for the PDF tails of heat flux. Furthermore, we present a detailed numerical study of the dependence of the PDF tail on the temperature and density scale lengths and other physical parameters through the coefficient {xi}.
- OSTI ID:
- 21120300
- Journal Information:
- Physics of Plasmas, Vol. 15, Issue 5; Other Information: DOI: 10.1063/1.2918338; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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