http://arxiv.org/abs/1903.08976
We study the effects of ambipolar diffusion (AD) on hydromagnetic turbulence. We use the strong coupling approximation where the drift velocity between ions and neutrals is proportional to the Lorentz force. We consider the regime of large magnetic Prandtl number, relevant to the interstellar medium. We quantify the effects of AD on total and spectral kinetic and magnetic energies, the Ohmic and AD dissipation rates, the statistics of the magnetic field, the current density, and the linear polarization as measured by the rotationally invariant $E$ and $B$ mode polarizations. We show that the kurtosis of the magnetic field decreases with increasing AD. The $E$ mode polarization changes its skewness from positive values for small AD to negative ones for large AD. Even when AD is weak, changes in AD have a marked effect on the skewness and kurtosis of $E$, and only a weak effect on those of $B$. These results open the possibility of employing $E$ and $B$ mode polarization as diagnostic tools to characterizing turbulent properties of the interstellar medium.
A. Brandenburg
Fri, 22 Mar 19
22/70
Comments: 8 pages, 8 figures, 1 table, submitted to NMRAS