Analysis of magnetic Rayleigh-Taylor instability in a direct energy conversion system which converts inertial fusion plasma kinetic energy into pulsed electrical energy

A direct energy conversion scheme to convert plasma kinetic energy into pulsed electrical energy, based on magnetic flux compression (MFC) by an inertial fusion plasma sphere, has been examined earlier. The plasma sphere, expanding across a magnetic field, is subject to the Magnetic Rayleigh-Taylor (MRT) instability. Therefore, 2D MHD simulations have been performed to analyze the MRT instability and its implications for the proposed MFC system. The simulation takes into account the effects of MFC and geometric divergence due to spherical plasma expansion. Single-mode sinusoidal perturbation evolution exhibits linear exponential growth followed by a non-linear phase towards stagnation time. We also note that near the time of stagnation, the growth in amplitude of the modes, although exponential in nature, is much lower than the growth predicted by linear theory. Furthermore, the instability amplitudes are not large enough for αin ⩽ 0.1λin to severely disturb the smooth MFC during the first expansion phase. However, the growth of modes with αin ⩾ λin causes plasma jetting, especially for longer λ modes, and can lead to significant reduction in MFC efficiency.