TY  - JOUR
A1  - Rüdiger, Günther
A1  - Küker, Manfred
A1  - Käpylä, Petri J.
T1  - Electrodynamics of turbulent fluids with fluctuating electric conductivity
JF  - Journal of plasma physics
N2  - Consequences of fluctuating microscopic conductivity in mean-field electrodynamics of turbulent fluids are formulated and discussed. If the conductivity fluctuations are assumed to be uncorrelated with the velocity fluctuations then only the turbulence-originated magnetic diffusivity of the fluid is reduced and the decay time of a large-scale magnetic field or the cycle times of oscillating turbulent dynamo models are increased. If, however, the fluctuations of conductivity and flow in a certain well-defined direction are correlated, an additional diamagnetic pumping effect results, transporting the magnetic field in the opposite direction to the diffusivity flux vector <eta'u'>. In the presence of global rotation, even for homogeneous turbulence fields, an alpha effect appears. If the characteristic values of the outer core of the Earth or the solar convection zone are applied, the dynamo number of the new alpha effect does not reach supercritical values to operate as an alpha(2)-dynamo but oscillating alpha Omega-dynamos with differential rotation are not excluded.
KW  - astrophysical plasmas
KW  - plasma flows
Y1  - 2020
U6  - https://doi.org/10.1017/S0022377820000665
SN  - 0022-3778
SN  - 1469-7807
VL  - 86
IS  - 3
PB  - Cambridge Univ. Press
CY  - London
ER  -