Numerical simulations of the ambipolar filamentation process

Abstract

We are carying out 2-D, two-fluid (ions and neutrals) numerical simulations of the ambipolar filamentation process, in which a magnetized, weakly ionized plasma is stirred by turbulence in the ambipolar frequency range. The higher turbulent velocity of the neutrals in the mast ionized regions gives rise to a non-linear force driving them out of these regions, so that the initial ionization inhomogeneities are strongly amplified. This effect, the ambipolar filamentation, causes the ions and the magnetic flux to condense and separate from the neutrals, resulting in a filamentary structure. This mechanism might help to explain some problems arising in magnetized and partially ionized astrophysical plasmas. It might provide an explanation for the spicules emerging from the solar photosphere. We also expect it to have an important role in star Formation. Under molecular cloud conditions (supersonic turbulence), we expect the mechanism to result in an additional pressure from the most ionized to the least ionized regions that efficiently separates the ions from the neutrals, favoring the gravitational collapse of the latter.