Magnetic energy spectrum produced by turbulent dynamo: effect of time irreversibility

Abstract

We consider the kinematic stage of evolution of magnetic field advected by turbulent hydrodynamic flow. We use a generalization of the Kazantsev-Kraichnan model to investigate time irreversible flows. In the viscous range of scales, the infinite-time limit of the spectrum is a power law but its slope is more flat than that predicted by Kazantsev model. This result agrees with numerical simulations. The rate of magnetic energy growth is slower than that in the time-symmetric case. We show that for high magnetic Prandtl turbulent plasma, the formation of the power-law spectrum shape takes very long time and may never happen because of the nonlinearity. We propose another ansatz to describe the spectrum shape at finite time.

References in corpus (6)

• Shell Models of Magnetohydrodynamic Turbulence
• Fluctuation dynamo at finite correlation times and the Kazantsev spectrum
• Magnetic dynamo action in random flows with zero and finite correlation times
• Non-Gaussian generalization of the Kazantsev-Kraichnan model
• Long-term properties of finite-correlation time isotropic stochastic systems
• Two-dimensional magnetohydrodynamic turbulence with large and small energy-injection length scales

Cited by in corpus (4)

• Long-term properties of finite-correlation time isotropic stochastic systems
• Suppression of small-scale dynamo in time irreversible turbulence
• Small-scale turbulent dynamo for low-Prandtl number fluid: comparison of the theory with results of numerical simulations
• Small-scale dynamo with finite correlation times