Asymptotic behavior of guiding-center diffusion in a model of electrostatic turbulence
- Physique Statistique et Plasmas, Code Postal 231, Universite Libre de Bruxelles, B-1050 Brussels (Belgium)
To compare with computer simulations of the diffusion of a test guiding center in a given electrostatic turbulence, a nonlinear theory is applied to the randomly phased waves'' model, with a single frequency [omega] and an arbitrary wave number spectrum. The asymptotic behavior of the diffusion coefficient [ital D] is determined in both limits of large and small turbulence amplitude [ital a]. For [ital a][r arrow][infinity], the classical frozen turbulence'' scaling [ital D][proportional to][ital a] is found. For [ital a][r arrow]0, an unusual quadratic scaling is obtained: for all isotropic models, [ital D] goes to the same limit ([radical]2 /[omega])[ital a][sup 2]. This behavior originates in the two scales'' character of this asymptotic problem. It is examined in detail on a simple form of the equation where the exact asymptotic solutions are obtained.
- OSTI ID:
- 7282725
- Journal Information:
- Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics; (United States), Vol. 50:1; ISSN 1063-651X
- Country of Publication:
- United States
- Language:
- English
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