Dynamic Inductance Testbed for Pulsed Power Flow Studies

Pulsed-power-driven high energy density (HED) experiments rely on the rapid delivery of energy from large capacitor banks to a target, typically through magnetically insulated transmission lines (MITLs). Conditions within these MITLs can be extreme, with multi-MA currents generating enormous electric and magnetic fields. This environment can fill the MITL with neutral and charged particles that can parasitically shunt the current and divert energy away from the target. While these effects have been numerically simulated and studied using surrogate platforms on smaller (1 MA) machines, such experiments have traditionally used targets with a fixed inductance. These platforms can reach comparable magnetic fields and current densities but lack the same electric fields and dynamic behavior associated with time-varying inductive loads. We present a novel test platform which can incorporate these and other features, such as x-ray illumination of the MITL test region. Simulations using Ansys Maxwell have characterized the anticipated EM fields over a representative current pulse. Initial testing on the 1-MA COBRA driver demonstrates the resulting plasma dynamics using visible spectroscopy, visible/UV imaging, interferometry, x-ray pinhole imaging, and photodiode measurements of plasma self-emission.