Probing the magnetic field with the Rayleigh-Taylor instability

We propose a nonlinear model for the single mode Rayleigh-Taylor instability subjected to a uniform magnetic field. This model generalizes the potential approach for purely hydrodynamics configurations initially proposed by Layzer [1] and then extended by Goncharov [2] to arbitrary Atwood numbers. It allows to derive the terminal bubble and spike velocities which are assessed against various 2D and 3D magnetohydrodynamics simulations. The model reveals that, contrary to the linear phase where the magnetic field inhibits the instability, it enhances the growth rate in the nonlinear regime. Conversely, we show how the orientation and the intensity of the magnetic field can be inferred from its solutions.