Development of a wire array current switch for Z*

The Z generator of Sandia National Laboratories typically delivers currents >20MA with rise times of ~100ns to a wide variety of experiments.  Both radiation sources and magneto-inertial-fusion (MIF) schemes are understood to benefit from shorter current pulses [1] but designing pulsed power systems to achieve faster current rise times is challenging.  An alternative is to introduce a plasma opening switch in close proximity to the intended target.  One approach that has been successfully demonstrated at the ~1MA scale [3] uses a low mass wire array to initially direct current away from the intended target.  This wire array ablates and explodes outwards, rapidly opening a direct current path to the target which is then driven by a current pulse that rises on a faster timescale set by the opening time of the switch.  As an example, the application of faster rise times to Magnetized Liner Inertial Fusion (MagLIF) targets may allow us to limit disruption from instabilities whilst increasing implosion velocities and improving stagnation performance [2].  We report on MHD simulations used to design and implement the exploding wire array style of current switch on Z, along with initial experiments to evaluate this concept.  We then discuss alternative wire array switch configurations that may limit the impact of opening switch plasma on the target by driving both target and switch in parallel.  The potential benefits and disadvantages of these alternative approaches to obtaining a faster rising current pulse will be examined and contrasted.

[1]      S. A. Slutz, Phys. Plasmas 25, 082707 (2018).

[2]      D. E. Ruiz et al., Phys. Plasmas 30, 032709 (2023).

[3]      G. C. Burdiak, Phys. Plasmas 22, 112710 (2015).