Design and Development of Laser Optical Imaging Diagnostics for Investigation of Low-Density Plasmas for Maglif Experiments

In magnetized liner inertial fusion (MagLIF) on the Z Machine [1] , a major concern is whether the magneto Rayleigh-Taylor (MRT) instability that forms in the liner can be sufficiently controlled to enable the assembly and confinement of a thermonuclear fusion fuel. MRT is observed to create helical plasma striations when an axial magnetic field is pre-embedded in the liner. One of the proposed origins of this so-called helical instability is from magnetic flux compression of a low-density plasma surrounding the liner. This plasma is hypothesized to originate from the high current densities on the transmission lines leading up to the liner. University of Michigan (UM) in collaboration with Sandia National Labs is developing a laser imaging suite that will provide density measurement capabilities to study these low-density plasmas and better understand their effects on the imploding liner. The two laser diagnostics under development are a laser schlieren refractometer [2] and a laser interferometer system, both with a 532-nm probe beam from a Nd:YAG laser. We present the design and development of the optical diagnostic suite along with surrogate experiments used to study these low-density plasmas on the MAIZE facility at UM, a 1-MA LTD pulsed power machine.