Early time studies of cylindrical liner implosions on COBRA

Tests of the magnetized liner inertial fusion (MagLIF) concept will make use of the 27 MA Z-machine at Sandia National Laboratories, Albuquerque, to implode a cylindrical metal liner to compress and heat a preheated plasma contained within it [1]. While most pulsed power machines produce much lower currents than the Z-machine, there are questions that can still be answered on smaller scale setups. Recent work on the Cornell Beam Research Accelerator (COBRA) has made use of cylindrical metal liners made in-house to study the initiation of plasma on the liner surface and axial magnetic field compression. Although such liners are not sufficiently uniform for MagLIF-relevant studies of liner dynamics during implosion, they can make early-time studies of cylindrical liner implosions viable for smaller laboratories. This paper will present experimental results of imploding liners having imperfect uniformity to assess the impact that has on initiation and ablation. Extreme ultraviolet (XUV) imaging as well as optical streak imaging is used to assess when and where non-uniform-driven emission occurs. Axial interferometry is used to determine the distribution of plasma near the liner surface, including the impact of non-uniformities during the plasma initiation and ablation phases of the experiments.