TY - JOUR
T1 - Dynamo in Weakly Collisional Nonmagnetized Plasmas Impeded by Landau Damping of Magnetic Fields
AU - Pusztai, István
AU - Juno, James
AU - Brandenburg, Axel
AU - Tenbarge, Jason M.
AU - Hakim, Ammar
AU - Francisquez, Manaure
AU - Sundström, Andréas
N1 - Publisher Copyright:
© 2020 authors. Published by the American Physical Society.
PY - 2020/6/26
Y1 - 2020/6/26
N2 - 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.
AB - 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.
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U2 - 10.1103/PhysRevLett.124.255102
DO - 10.1103/PhysRevLett.124.255102
M3 - Article
C2 - 32639756
AN - SCOPUS:85087708415
SN - 0031-9007
VL - 124
JO - Physical review letters
JF - Physical review letters
IS - 25
M1 - 255102
ER -