Development of laser imaging diagnostics for the Mykonos and Z Pulsed Power Accelerators

Low-density plasmas are hypothesized to drive several MA of current loss on the Z Machine by redistributing current in the transmission line leading up to the target region. These low-density plasmas are well suited for diagnosis via laser probing. In this work, we present the design and development of laser interferometry and Faraday Rotation imaging diagnostics for measuring electron density and magnetic field profiles on the 1-MA Mykonos Pulsed Power Accelerator in preparation for deployment on the 27-MA Z Machine. The interferometry design incorporates a Wollaston prism to compactly allow splitting of a single laser image with sufficient beam overlap for fringe formation. Unlike more common interferometry methods such as the Mach-Zehnder or Nomarski type, using a Wollaston prism allows for an easily adjustable setup where the spacing of the fringes, and therefore sensitivity of the diagnostic to electron density, can be easily manipulated by sliding the prism along the laser light path. In our commissioning work on Mykonos, we acquired an interferogram of a hybrid X-pinch. The distinct fringe boundaries will allow for accurate measurements of fringe displacement to spatially resolve the line integrated electron density of the plasma. Future efforts will leverage this system alongside shadowgraphy and Faraday rotation imaging to examine plasma magnetic fields on Z.