Improved Stability and Reproducibility of Magnetized Liner Inertial Fusion Implosions

The Magnetized Liner Inertial Fusion (MagLIF) approach uses a pulsed-power-driven low-Z liner to compress a pre-magnetized, pre-heated fuel to reach fusion conditions. As with all inertial confinement fusion schemes, implosion stability is a key factor in the success of MagLIF. Since the first MagLIF experiments, there has been evidence of non-uniform implosions, with a quasi-helical stagnation column and significant variations in x-ray brightness along the height of the column. Recent experiments varied the aspect ratio of the liner and demonstrated a change in stagnation structures, consistent with an instability being seeded on the outer surface of the liner. To minimize the electro-thermal instability, a likely seed for magneto-Rayleigh Taylor growth, we incorporated a CH coating on the outer surface of the beryllium liner. Using this coating we achieved a stagnation column with negligible helical structure and minimal axial variation in x-ray brightness. The first data from a one-dimensional neutron imager also showed quasi-uniform neutron emission along the stagnation column. By creating a quasi-uniform stagnation column, we improved stagnation reproducibility, with <15% shot-to-shot variability in ion temperature, DD yield, and, importantly for magneto-inertial schemes, magnetization. Building on this reproducible platform we will discuss experiments that have started to make controlled changes, including experiments that show an increase in ion temperature and yield at stagnation with increased pre-magnetization.