Helical deformation of 3D defect in premagnetized Z-pinch liner

The magnetized liner inertial fusion (MagLIF) concept uses an azimuthal magnetic field (B_θ) to compress a metallic liner containing fusion fuel. A key component of MagLIF is an axial magnetic field B_z, permeating both the fuel and surrounding liner, which reduces the compression necessary to achieve fusion conditions. Experiments demonstrate that a liner premagnetized with B_z develops a helical instability with a pitch significantly larger than predicted by magnetohydrodynamic (MHD) theory. The cause of the helical instability remains an open research question. In this work, we examine the possible role of three-dimensional (3D) defects, which commonly occur in metals, as a seed for the helical instability. In general, a defect constitutes a nonlinear perturbation to the electrical current flow, which initiates a 3D feedback loop that allows the defect to grow and transform. In this work, we use 3D MHD simulations to examine how B_z modifies this feedback loop, thus causing a defect to deform helically. Simulation predictions can be tested experimentally, through visible emission imaging.