EFFECT of Dynamic AXIAL Magnetic Mirror on Low-Number Aluminum Wire-Array Z-Pinch

Dynamic magnetic mirror configurations produced using auto-magnetizing liners have the potential to reduce plasma end-losses in MagLIF [1] . Motivated by this possibility, we investigate the dynamics of composite, auto-magnetizing array implosions on the 1-MA, 100-ns rise time COBRA generator. The annular array consists of eight anode and eight cathode stainless steel tubes through which 17-μm diameter aluminum wires are threaded. 1 cm of the wires are exposed between the anode and cathode tubes to generate the z-pinch plasma. Independent twists in the tube and wire sections modify current direction to form an axial magnetic mirror with adjustable mirror ratio. Plasma dynamics of the mirror configuration and the control implosions with straight tubes are compared. Array configuration that applies a 1.5-T axial field at peak current with a mirror ratio of 2 exhibits a reduced and more localized soft X-ray emission compared to control. Reverse-twisting of the wire array to reduce the local axial field magnitude increases the x-ray yield of the mirror configuration. Magnetohydrodynamic simulations used to guide experimental design and investigate the detailed dynamics are also presented.