Hydrodynamic instabilities are ubiquitous in pinched implosion scenarios, leading to loss of energy for compression and to mix of dissimilar materials. In order to study them and assess their impact on more integrated experiments, dedicated instability experiments are performed. We present experimental results from a suite of platforms investigating the Richtmyer-Meshkov process and interfacial feedthrough on the Z Machine at Sandia National Laboratories. Cylindrical liners filled with liquid deuterium are magnetically imploded with >20 MA of current, driving a converging shock toward the central axis and creating a magnetically isolated region suitable for studying hydrodynamic processes. The first platform investigates the interaction of this shock with a solid beryllium rod machined with sinusoidal perturbations that then grow under the Richtmyer-Meshkov process. The second platform replaces the on-axis rod with a cylindrical liner, enabling investigation of the feedthrough of these instabilities to the inner liner surface. Simulations of the liner implosion and subsequent instabilities are presented from the xRAGE, GORGON, and ALEGRA radhydro codes. Finally, future experimental platforms will be discussed, including an exploding cylindrical liner system to study the Rayleigh-Taylor instability driven for >100 ns to a highly nonlinear regime.

This work conducted under the auspices of the U.S. DOE by Los Alamos National Laboratory under contract 89233218CNA000001 and by Sandia National Laboratories under contract DE-NA0003525. LA-UR-23-24109

Magnetized Liner Inertial Fusion (MagLIF) is a magneto-inertial-fusion concept that is studied at Sandia National Laboratories on the 20-MA, 100-ns rise-time Z Pulsed Power Facility at Sandia National Laboratories. Given the relative success of the platform, there is a wide interest in studying the scaled performance of this concept at a Next Generation Pulsed Power (NGPP) facility that may produce peak currents upwards of 60 MA. An important aspect that requires more research is the instability dynamics of the imploding MagLIF liner, specifically how instabilities are initially seeded. It has been shown in magnetized 1-MA thin-foil liner Z-pinch implosion simulations that a Hall interchange instability (HII) effect¹ can provide an independent seeding mechanism for helical Magneto-Rayleigh-Taylor instabilities. In this presentation, we study the dynamics of the HII in MagLIF driven at higher peak currents. In this study, we use the 2D Discontinuous Galerkin PERSEUS code, an extended magneto-hydrodynamics code,² which includes Hall physics. Our simulations of scaled MagLIF loads show that the Hall interchange instability remains an important effect at high currents.

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the U.S. Department of Energy or the United States Government.

1) J. M. Woolstrum, C. E. Seyler, and R. D. McBride, “Hall instability driven seeding of helical magneto-rayleigh–taylor instabilities in axially premagnetized thinfoil liner z-pinch implosions,” Physics of Plasmas 29, 122701 (2022), https://doi.org/10.1063/5.0103651, URL https://doi.org/10.1063/5.0103651.

2) C. E. Seyler and M. R. Martin, “Relaxation model for extended magnetohydrodynamics: Comparison to magnetohydrodynamics for dense Z-pinches,” Physics of Plasmas 18, 012703 (2011), ISSN 1070-664X, URL http://aip.scitation.org/doi/10.1063/
1.3543799.