Enhancement of Ambipolar Diffusion Rates through Field Fluctuations

Tracing Turbulent Ambipolar Diffusion in Molecular Clouds

Though flux freezing is a good approximation frequently assumed for molecular clouds, ambipolar diffusion (AD) is inevitable at certain scales. The scale at which AD sets in can be a crucial parameter for turbulence and the star formation process. However, both observation and simulation of AD are very challenging and our knowledge of it is very limited. We recently proposed (Li and Houde 2008)...

Ambipolar diffusion in the magnetorotational instability

The effects of ambipolar diffusion on the linear stability of weakly ionised accretion discs are examined. Earlier work on this topic has focused on axial magnetic fields and perturbation wavenumbers. We consider here more general field and wavenumber geometries, and find that qualitatively new results are obtained. Provided a radial wavenumber and azimuthal field are present along with their a...

Large scale dynamos with ambipolar diffusion nonlinearity

It is shown that ambipolar diffusion as a toy nonlinearity leads to very similar behaviour of large scale turbulent dynamos as full MHD. This is demonstrated using both direct simulations in a periodic box and a closure model for the magnetic correlation functions applicable to infinite space. Large scale fields develop via a nonlocal inverse cascade as described by the alpha-effect. However, b...

Field observations on population fluctuations of chicory aphids 1970

Tauri disk winds heated by ambipolar diffusion I - Thermal structure

Motivated by recent subarcsecond resolution observations of jets from T Tauri stars, we extend the work of (Safier 1993a,b) by computing the thermal and ionization structure of self-similar, magnetically-driven, atomic disk winds heated by ambipolar diffusion. Improvements over his work include: (1) new magnetized cold jet solutions consistent with the underlying accretion disk (Ferreira 1997);...