2002/08/07 by Abhik Basu, Basu, Abhik
Physics and Astronomy · #Chaotic Dynamics (nlin.CD) #FOS: Physical sciences #nlin.CD
paper · pdf · doi:10.48550/arxiv.nlin/0208010
LaTex, 2 .eps files for figures, submitted to Phys. Rev. E
arxiv created 2002/08/07 · arxiv updated 2009/11/30
The turbulent dynamo effect, which describes the generation of magnetic fields in astrophysical objects, is described by the dynamo equation. This, in the kinematic (linear) approximation gives an unbounded exponential growth of the long wavelength part of the magnetic fields. Here we, in a systematic diagrammatic, perturbation theory, show how non-linear effects suppress the linear instability and bring down the growth rate to zero in the large time limit. We work with diffferent background velicity spectrum and initial magnetic field correlations. Our results indicate the robustness and very general nature of dynamo growth: It is qualitatively independent of the background velicty and intial magnetic field spectra. We also argue that our results can be justified within the framework of the first order smoothing approximation, as applicable for the full non-linear problem. We discuss our results from the view points of renormalisation group analysis.