Study of the Initiation Phase of Thick, Metallic Liners at 1MA

We present a study investigating the initiation of plasma in solid, metallic liners where the liner thickness is large compared to the collisionless skin depth. The current pulse on the 1 MA, 100ns COBRA generator is comparable to the early stages of the current pulse on the Z generator, and studies in the low current regime may highlight details of the liner initiation pertinent to the MagLIF fusion scheme [1]. We present optical emission data from aluminum liners using gated imaging and streak photography, which show a dependence of onset of emission with the size of a small power-feed gap introduced at the cathode. We also show measurements of the B-field inside the liner, using miniature Bdot probes, which show a dependence on the liner diameter and thickness. These data will be compared to magneto-hydrodynamic simulations. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. Work at Cornell University is supported by the NNSA-SSAA through Cooperative Agreement DE-FC03-02NA00057. \\[4pt] [1] Slutz et al, Phys Plasmas, 17, 056303 (2010)