Separatrix crossing and large scale diffusion in low-frequency three-wave systems
The E x B guiding centre (GC) diffusion in three low-frequency 2-dimensional electrostatic waves is considered. It is shown that the stochastic GC diffusion can be explained and predicted with the help of the rules of the adiabatic theory of Hamiltonian systems: conservation of the canonical action except at separatrix crossing times; time evolution of the canonical action determined by the surfaces enclosed by the separatrices of the potential. The probability distributions are calculated. A statistical analysis of the dynamics shows that the GC motion is a spaced constrained random walk governed by a "complete trapping" scaling law for diffusion. This result is demonstrated both semi-analytically and numerically.
Bibliographic Reference: Report: EUR-CEA-FC-1634 EN (1998) 10pp.
Availability: Available from Association Euratom-CEA, CEN Cadarache, 13108 Saint-Paul-lez-Durance (FR)
Record Number: 199811007 / Last updated on: 1998-09-15
Original language: en
Available languages: en