http://arxiv.org/abs/1403.1328
We have studied the influence of initially given small scale magnetic energy($E_M(0)$) and helicity($H_M(0)$) on the magnetohydrodynamics(MHD) dynamo using simulations and analytic methods. $E_M$(0) in small scale boosts the growth of the large scale magnetic field($\overline{{\bf B}}$). The rate is also proportional to $H_M(0)$; i.e., positive $H_M(0)$ is more effective than negative $H_M(0)$. $E_M$(0) and $H_M$(0) generate the additional electromotive force($EMF$) terms. The effect of initial conditions($IC$s) depends on magnetic diffusivity $\eta$, position of $IC$s $k_f$, and time($e^{-\eta k_f^2 t}$). Complete large scale $E_M$(t) and $H_M$(t) were derived using the mean field theory. It was discussed why large scale magnetic helicity should have the opposite sign of the injected kinetic helicity. The physical meaning of $H_M$ subject to $E_M$ was also briefly discussed.
K. Park
Fri, 7 Mar 14
19/47