Use of synchrotron-based radiography to diagnose pulsed power driven wire explosion experiments

Abstract

We describe the first use of synchrotron radiation to probe pulsed power driven high energy density physics experiments. Multiframe x-ray radiography with interframe spacing of 704 ns and temporal resolution of <100 ps was used to diagnose the electrical explosion of different wire configurations in water including single copper and tungsten wires, parallel copper wire pairs, and copper x-pinches. Such experiments are of great interest to a variety of areas including equation of state studies and high pressure materials research, but the optical diagnostics that are usually employed in these experiments are unable to probe the areas behind the shock wave generated in the water, as well as the internal structure of the exploding material. The x-ray radiography presented here, performed at beamline ID19 at European Synchrotron Radiation Facility (ESRF), was able to image both sides of the shock to a resolution of up to 8 µm, and phase contrast imaging allowed fine details of the wire structure during the current driven explosion and the shock waves to be clearly observed. These results demonstrate the feasibility of pulsed power operated in conjunction with synchrotron facilities, as well as an effective technique in the study of shock waves and wire explosion dynamics.

A portable X-pinch design for x-ray diagnostics of warm dense matter

“…Once the system is charged, a trigger voltage is provided by an external TG75 vector inversion generator that capacitatively couples to the second row of balls in the switch via a stripped RG214 coaxial cable. It delivers a 75 kV trigger pulse into an open-ended 9), the load-locking ring (10), the X-pinch load (11), and the top anode plug (12). The direction of electron flow within the device is indicated by red arrows before the load and by blue arrows after the load.…”

“…Upon closing of the switches, the capacitors discharge in parallel through a converging conical section (6) into the magnetically insulating transmission line (MITL) (7) with a nonintegrating Rogowski coil placed within the casing to measure the current flow through the transmission line (8). The current is then guided through a gently converging cathode (9) and a load locking ring (10), through the X-pinch load (11), and straight into the anode (12), which is connected to ground via the external casing.…”

“…9 These diagnostics can be driven by large high-energy laser-matter interaction experiments at national facilities 8 such as the Laboratory for Laser Energetics (LLE) and the Rutherford Appleton Laboratory (RAL). In some cases, experiments can also be temporarily relocated to take advantage of thirdgeneration synchrotrons 9,10 or x-ray free-electron lasers (XFELs); however, in many cases, this option is not available. Further, even for experiments where relocation to external facilities is possible, there is a considerable benefit in having on-site x-ray diagnostics to obtain preliminary data and optimize the experiment prior to facility beam time.…”

“…It is possible to use different designs for the load section with different A-K gaps or shapes/numbers of output windows. (f) CAD model of the mounting mechanism, including the cathode (9), the load-locking ring(10), the X-pinch load(11), and the top anode plug(12). The direction of electron flow within the device is indicated by red arrows before the load and by blue arrows after the load.…”

Experiments on plasma dynamics of electrical wire explosion in air

“…Theocharous et al. imaged the details of two parallel Cu explosions in water with the help of a synchrotron radiation source and demonstrated the instabilities of DC caused by shock waves [30]. Wang et al.…”