Mean-field dynamo in partially ionized plasmas-I - AstrophysicsReport as inadecuate

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Abstract: There are several astrophysical situations where one needs to study thedynamics of magnetic flux in partially ionized turbulent plasmas. In apartially ionized plasma the magnetic induction is subjected to the ambipolardiffusion and the Hall effect in addition to the usual resistive dissipation.In this paper we initiate the study of the kinematic dynamo in a partiallyionized turbulent plasma. The Hall effect arises from the treatment of theelectrons and the ions as two separate fluids and the ambipolar diffusion dueto the inclusion of neutrals as the third fluid. It is shown that thesenonideal effects modify the so called $\alpha$ effect and the turbulentdiffusion coefficient $\beta$ in a rather substantial way. The Hall effect mayenhance or quench the dynamo action altogether. The ambipolar diffusion bringsin an $\alpha$ which depends on the mean magnetic field. The new correlationsembodying the coupling of the charged fluids and the neutral fluid appear in adecisive manner. The turbulence is necessarily magnetohydrodynamic with newspatial and time scales. The nature of the new correlations is demonstrated bytaking the Alfv\-enic turbulence as an example.

Author: V. Krishan, R.T. Gangadhara Indian Institute of Astrophysics, Raman Research Institute


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