  The self-generated magnetic field in three-dimensional (3D) single-mode
ablative Rayleigh-Taylor instabilities (ARTI) relevant to the acceleration
phase of a direct-drive inertial confinement fusion (ICF) implosion is
investigated. It is found that stronger magnetic fields up to a few thousands
of T can be generated by 3D ARTI than by its two-dimensional (2D) counterpart.
The Nernst effects significantly alter the magnetic fields convection and
amplify the magnetic fields. The scaling law for the magnetic flux obtained in
the 2D simulations performs reasonably well in the 3D cases. While the magnetic
field significantly accelerates the bubble growth in the short-wavelength 2D
modes through modifying the heat fluxes, the magnetic field mostly accelerates
the spike growth but has little influence on the bubble growth in 3D ARTI.
