Magnetic Field Measurements in Wire-Array Z-Pinches

A method to determine the magnetic field in megampere level wire-array Z-pinches with high spatial and temporal resolution has not yet been developed. An ideal method would be passive and non-perturbing, such as Faraday rotation of laser light or emission spectroscopy. However, Faraday rotation measurements in Z-pinches suffer from severe difficulties, because density gradients are large and the plasma is magnetohydrodynamically turbulent inside the Z-pinches. Therefore, we are developing a method based on Faraday rotation through a sensing waveguide placed in the vicinity of, or perhaps in, a wire-array Z-pinch. We will also discuss emission spectroscopy methods based upon the Zeeman effect that are also under investigation. Finally, we will present a technique developed using magnetic CoPt thin films that measures a lower limit for the maximum magnetic field.