Role of magnetic fields on Rayleigh-Taylor instability

The magnetic Rayleigh Taylor instability (MRTI) is ubiquitous in a wide range of astrophysical and laboratory systems. However, the evolution and the dynamics of MRTI is not fully understood. Magnetic fields play a crucial role in the instability dynamics of these systems. Towards understanding the interplay between gravity and magnetic forces on the evolution of instability, we study MRTI under simplified setting using analytical and numerical techniques. Our study shows that the imposed magnetic field delays the onset of self-similarity. However, when sufficiently evolved, MRTI grew with similar temporal scaling as HD instability. The study revealed various physical processes, like energy dissipation (ED), kinetic and magnetic energy partition that determine the non-linear growth of instability across a wide range of magnetic field strengths. A particularly interesting finding is the drastic increase in energy dissipation with marginal increase in field strength, with magnetic ED thrice the kinetic ED for all field strengths. To understand this surprising behaviour, we investigate the potential role of magnetic reconnection. A new technique for the detection of magnetic reconnection sites was developed. Quantitative analysis of these showed that the weak fields have greater reconnection events with small RMS current, while the strong fields have lesser reconnection events but with large RMS current. This could potentially be responsible for greater ED at intermediate fields where the number of reconnection events and mean RMS current optimize to result in maximum energy dissipation. We aim to further investigate the role of magnetic reconnection on MRTI dynamics. Thus, the current study presents a comprehensive understanding on the influence of magnetic fields on the evolution and growth of non-linear MRTI, and the impact of magnetic reconnection on MRTI dynamics. The unspecialized configuration meant the results are applicable in a wide range of practical systems.