Megagauss magnetic fields and surface plasmas: Physical insight, computational issues

Abstract

Summary form only given. Megagauss magnetic fields on metallic surfaces form plasmas that have higher temperatures than would be expected based upon simple diffusion models, as has been demonstrated by a series of aluminum “thick-wire,” i.e., rod, experiments that have been conducted on the University of Nevada, Reno (UNR) Zebra generator (2 TW, 1 MA, 100 ns). One physical situation of current interest where such fields and plasmas may be encountered is Magnetized Target Fusion (MTF), where magnetically driven liners compress magnetized plasmas to fusion temperatures, e.g., the Russian MAGO program, the MagLIF program recently initiated at the Sandia National Laboratories and the FRCHX experiments being conducted at the Air Force Research Laboratory. Computations by Garanin and the UNR team have predicted and/or “matched” many of the previously reported Zebra experimental observations, including an observed magnetic field threshold for surface plasma formation. In this paper we report Eulerian computations that show improved agreement with the observations. It is quite common to use computations that “match the experiment” to interpret the experimental results, and we report an interpretation based upon the Eulerian results. However, we have also compared the Eulerian computations with the Lagrangian calculations of Garanin and Lagrangian calculations performed with the computer code Raven. The comparisons between the codes give rise to serious concerns about the differences between Eulerian and Lagrangian simulations and about the differences between van der Waals and Maxwell-construct equations-of-state.