X-ray Thomson Scattering From Spherical Implosions on the OMEGA Laser

Alison Saunders, University of California, Berkeley

X-ray Thomson scattering (XRTS) is an experimental technique that can directly probe the complicated physics of warm and hot dense matter. The Compton-shifted profile of inelastically scattered X-rays reflects the electron velocity distribution and provides a way of measuring the electron density and temperature1]. The ratio of elastically versus inelastically scattered X-rays is related to the number of tightly bound versus free electrons, and thus reflects the ionization state of the sample1. Recent experiments performed on the Linac Coherent Light Source at the SLAC National Accelerator Laboratory, the OMEGA laser at the Laboratory for Laser Energetics, and at the National Ignition Facility at Lawrence Livermore National Laboratory shed light on uncertainties in the ionization models often used to describe warm dense matter2-4. More experimental validation of these models is needed to understand the complex behavior of warm dense matter. We present experimental platforms to conduct XRTS measurements on directly driven and hohlraum-driven solid spheres at OMEGA; the platforms extend upon previously successful XRTS measurements from directly driven spherical shells3,5. Twenty to 50 laser beams drive the hohlraum or directly drive the spherical sample. Six to eight lasers drive a zinc foil to produce a zinc He- X-ray source at 9 keV, used for the XRTS measurements. The laser drive can be scaled in intensity to scale the conditions reached in the compressed spherical sample. We will present experimental results from carbon-containing samples, which were driven into conditions where carbon K-shell ionization becomes possible.

References:
1S.H. Glenzer and R. Redmer. Rev. Mod. Phys. 81, 1625 (2009).
2D. Kraus et al., Phys. Rev. E. 94, 011202(R) (2016).
3L.B. Fletcher et al., Phys. Rev. Lett. 112, 145004 (2014).
4O. Ciricosta et al., Nat. Comm. 7, 11713 (2016).
5A. Kritcher et al., Phys. Rev. Lett. 107, 015002 (2011).

Abstract Author(s): Alison M. Saunders, Amy Lazicki-Jenei, Tilo Doeppner, Otto Landen, Michael MacDonald, Joe Nilsen, Damian Swift, Roger W. Falcone