Turbulent dynamo in a collisionless plasma

François Rincon (a,b), Francesco Califano (c), Alexander A. Schekochihin (d,e), and Francesco Valentini (f)

Although magnetic field amplification by a dynamo effect converting kinetic flow energy into magnetic energy has long been shown in conventional magnetohydrodynamic fluids, whether a similar effect is possible in more dynamically complex weakly collisional plasmas, such as those encountered in astrophysical objects on extragalactic scales, is not known. We present the first, to our knowledge, conclusive numerical evidence and dynamical picture of magnetic field amplification by chaotic motions in a collisionless plasma. The results suggest that such a plasma dynamo may be a realizable physical effect in “laboratory astrophysics” experiments and support the idea that turbulent dynamos may significantly contribute to the magnetization of weakly collisional high-energy density astrophysical plasmas, such as the intracluster medium of galaxy clusters.

PNAS - Proceedings of the National Academy of  Sciences of the United States of America
vol. 113 no. 15 pp. 3950-3953
DOI: 10.1073/pnas.1525194113
Published: April 12,2016

(a) Université de Toulouse, Université Paul Sabatier-Observatoire Midi-Pyrénées, Institut de Recherche en Astrophysique et Planétologie, Toulouse, France;
(b) CNRS, Institut de Recherche en Astrophysique et Planétologie, Toulouse, France
(c) Physics Department, University of Pisa, Pisa, Italy
(d) The Rudolf Peierls Centre for Theoretical Physics, University of Oxford, Oxford, United Kingdom
(e) Merton College, Oxford, United Kingdom
(f) Dipartimento di Fisica, Universitá della Calabria, Rende (CS), Italy