Multi-mode Magneto-Rayleigh-Taylor instability growth experiments in pulsed power liners

Summary form only given. The presence of Magneto-Rayleigh-Taylor (MRT) instabilities limit the achievable controlled compression of fusion fuel in pulsed power inertial confinement fusion concepts such as MagLIF [1]. It is therefore essential to not only mitigate the growth of MRT instabilities to the extent possible, but also validate simulation tools used to evaluate and assess MRT instability growth in these types of targets. Previously, we have shown single mode MRT experiments in solid Al liners that have proven extremely fruitful in benchmarking instability growth in several simulation codes [2]. It is also important to test our understanding and validate simulation predictions of multimode MRT growth. Computational studies of multimode perturbations have been done in the past with wire array z-pinch implosions [3]. However, heretofore no experiment has been performed to quantitatively study either linear or nonlinear multimode MRT instability growth in a controlled manner. In this paper, we discuss new simulations and experiments designed specifically to investigate multimode MRT instability growth. These experiments utilize x-ray radiography to measure the growth of two superimposed sinusoidal perturbations (400 gm and 550 gm in wavelength with peak to valley amplitudes of 20 gm) imposed on solid Al liners 292 gm thick with an initial outer radii of 3.16 mm. These experiments are also designed to evaluate MRT growth in the quasi-linear and nonlinear regimes. As such, we will also discuss effects such as the generation of higher order mode harmonics, mode saturation, and mode coupling.