Laser Optical Imaging Diagnostics for Investigation of Low-Density Plasmas for MagLIF Experiments

One of the major concerns in magnetized liner inertial fusion (MagLIF) experiments on Z is the development of the magneto Rayleigh-Taylor (MRT) instability, which causes degradation to the confinement of thermonuclear fuel. MRT is observed to create helical plasma striations when an axial magnetic field is pre-embedded along the liner with external coils. A hypothesis for the origin of this so-called helical instability is from magnetic flux compression of a low-density plasma (LDP) around the liner originating from the high current densities on the transmission lines leading up to the liner. To study this hypothesis, we are developing a suite of laser-based diagnostics that will provide temporally resolved images as well as density measurements capable of studying LDPs and their interaction onto an 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 development of the optical diagnostic suite along with a surrogate liner experiment used to study LDPs on the University of Michigan's MAIZE facility, a 1-MA class linear transformer driver.