X-ray diagnostic development for electron beam driven WDM studies*

A platform for characterizing the equation-of-state of the warm dense matter (WDM) regime is being developed on an intense, relativistic electron accelerator^1,2. An 80-ns (FWHM) electron pulse with a beam current of 1.7 kA and energy of 19.8 MeV deposits energy into a thin, low-Z metal foil heating it to a warm dense plasma. LASNEX hydrodynamic simulations suggest the relatively large scale (~100 μm) WDM lasts 100 ns after the beam pulse providing a background-free measurement window for deploying X-ray diagnostics. Time-resolved X-ray shadowgraphy will be used to measure the spatial extent of the WDM. X-ray absorption spectroscopy can measure the temperature and density of the WDM by tailoring backlighter/crystal pairs to the plasma under interrogation. Calculations and simulations will be presented to evaluate the feasibility of different X-ray sources and detection techniques for each diagnostic. Full scale Geant4 simulations to estimate photon yields and guide experimental deployment are underway.

1. J.E. Coleman and J. Colgan, Phys. Rev. E 96, 013208 (2017).
2. J.E. Coleman and J. Colgan, Physics of Plasmas 24, 083302 (2017).