Experimental investigation of the effects of an axial magnetic field on the magneto Rayleigh-Taylor instability in ablating planar foil plasmas

Summary form only given. Experiments are underway to study the effects an axial magnetic field on the magneto Rayleigh-Taylor instability (MRT) in ablating planar foils on the 1-MA LTD at the Michigan Accelerator for Inductive Z-pinch Experiments (MAIZE) facility at the University of Michigan. In planar foil ablation experiments at UM, MRT is observed when the expanding plasma-vacuum interface decelerates as the magnetic pressure exceeds the plasma pressure during the drive current¹. Theoretical investigation at UM has shown that an axial magnetic field along with magnetic shear may reduce the MRT growth rate in general². To test this experimentally, axial magnetic fields are generated using helical return current posts. The axial field is proportional to the drive current and peaks at 13 T for 600 kA peak current. A 775 nm Ti:sapphire laser is used to shadowgraph the foil in order to study the MRT instability. Results indicate improved confinement in addition to significant anisotropy on the left and right sides of the foil when compared to experiments at UM using planar return current posts with no axial field. Recent work utilizes a new load configuration where return current plates run perpendicular to the foil current, producing an axial field that can be adjusted based on the proximity of the plates to the foil.