Wire-Array Z-pinch within a Dynamic Magnetic Mirror

A dynamic axial magnetic mirror could reduce end losses of cylindrical magneto-inertial fusion targets and could be implemented in MAGLIF experiments using auto-magnetizing liners to increase fuel density. To study the plasma confinement by a pulsed-power driven dynamic mirror, COBRA, a 1MA, 100-ns rise time pulsed-power machine, was used to implode arrays of wires threaded through twisted tubes that form helical current paths on the two ends to produce the mirror field. The wire arrays are composed of 8 Al wires with a wire diameter of 17 μm, an initial array diameter of 11 mm and an array length of 10 mm. Two mirror designs with a mirror ratio of 2 and peak mid-point axial magnetic fields of 0.77 T and 1.5 T respectively are tested along with the standard Z-pinch control case without any axial/mirror field. The pinch dynamics are monitored by a 12-frame optical high-speed camera, and XUV pinhole cameras while time-resolved X-ray power measurements were collected by a set of diamond PCDs and Si diodes. The high field case (1.5 T) showed an improved repeatability over the control case in the integrated PCD signal that corresponds to the total X-ray yield. Shot experiments with the dynamic magnetic mirror were also done with wire arrays twisted in the opposite direction to produce an opposing axial magnetic field.