  3-D extended-MHD simulations of the magnetized ablative Rayleigh-Taylor
instability are presented for the first time. Previous 2-D simulations claiming
perturbation suppression by magnetic tension are shown to be misleading, as
they do not include the most unstable dimension. For perturbation modes along
the applied field direction, the magnetic field simultaneously reduces ablative
stabilization and adds magnetic tension stabilization; the stabilizing term is
found to dominate for applied fields >5T, with both effects increasing in
importance at short wavelengths. For modes perpendicular to the applied field,
magnetic tension does not directly stabilize the perturbation, but can result
in moderately slower growth due to the perturbation appearing 2-D (albeit in a
different orientation to 2-D ICF simulations). In cases where thermal ablative
stabilization is dominant the applied field increases the peak bubble-spike
height. Resistive diffusion is shown to be important for short wavelengths and
long timescales, reducing the effectiveness of tension stabilization.

Plasma Physics;Computational Physics;Fluid Dynamics