Dynamo in Weakly Collisional Nonmagnetized Plasmas Impeded by Landau Damping of Magnetic Fields

István Pusztai, James Juno, Axel Brandenburg, Jason M. Tenbarge, Ammar Hakim, Manaure Francisquez, Andréas Sundström

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13 Scopus citations

Abstract

We perform fully kinetic simulations of flows known to produce dynamo in magnetohydrodynamics (MHD), considering scenarios with low Reynolds number and high magnetic Prandtl number, relevant for galaxy cluster scale fluctuation dynamos. We find that Landau damping on the electrons leads to a rapid decay of magnetic perturbations, impeding the dynamo. This collisionless damping process operates on spatial scales where electrons are nonmagnetized, reducing the range of scales where the magnetic field grows in high magnetic Prandtl number fluctuation dynamos. When electrons are not magnetized down to the resistive scale, the magnetic energy spectrum is expected to be limited by the scale corresponding to magnetic Landau damping or, if smaller, the electron gyroradius scale, instead of the resistive scale. In simulations we thus observe decaying magnetic fields where resistive MHD would predict a dynamo.

Original languageEnglish (US)
Article number255102
JournalPhysical review letters
Volume124
Issue number25
DOIs
StatePublished - Jun 26 2020

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy

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