AMBIPOLAR FILAMENTATION OF TURBULENT MAGNETIC-FIELDS

We show that turbulence in a weakly ionized plasma can lead to a filam entation of magnetic flux tubes as it reaches the ambipolar scale, whe re the neutrals are imperfectly coupled to the ions. This results from an instability mechanism, forcing the neutrals outside of the more io nized regions and compressing the ions and the field in these regions. It might have important consequences in such astrophysical contexts a s the solar atmosphere or the interstellar medium.