par De Leener, Michel
Référence Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics, 50, 1, page (502-512)
Publication Publié, 1994
Article révisé par les pairs
Résumé : 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 ω and an arbitrary wave number spectrum. The asymptotic behavior of the diffusion coefficient D is determined in both limits of large and small turbulence amplitude a. For a→, the classical "frozen turbulence" scaling Da is found. For a→0, an unusual quadratic scaling is obtained: for all isotropic models, D goes to the same limit (2 /ω)a2. 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. © 1994 The American Physical Society.