Observations of continuum depression in warm dense matter with x-ray Thomson scattering
L B Fletcher1, A L Kritcher2, A Pak2
1SLAC National Accelerator Laboratory, 2575 Sand Hill Road, MS 72 Menlo Park, California 94025, USA and Physics Department, University of California, Berkeley, California 94720, USA.
Abstract:
Detailed measurements of the electron densities, temperatures, and ionization states of compressed CH shells approaching pressures of 50 Mbar are achieved with spectrally resolved x-ray scattering. Laser-produced 9 keV x-rays probe the plasma during the transient state of three-shock coalescence. High signal-to-noise x-ray scattering spectra show direct evidence of continuum depression in highly degenerate warm dense matter states with electron densities ne>1024 cm-3. The measured densities and temperatures agree well with radiation-hydrodynamic modeling when accounting for continuum lowering in calculations that employ detailed configuration accounting.
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