  In the laboratory study of extreme conditions of temperature and density, the
exposure of matter to high intensity radiation sources has been of central
importance. Here we interrogate the performance of multi-layered targets in
experiments involving high intensity, hard x-ray irradiation, motivated by the
advent of extremely high brightness hard x-ray sources, such as free electron
lasers and 4th-generation synchrotron facilities. Intense hard x-ray beams can
deliver significant energy in targets having thick x-ray transparent layers
(tampers) around samples of interest, for the study of novel states of matter
and materials' dynamics. Heated-state lifetimes in such targets can approach
the microsecond level, regardless of radiation pulse duration, enabling the
exploration of conditions of local thermal and thermodynamic equilibrium at
extreme temperature in solid density matter. The thermal and mechanical
response of such thick layered targets following x-ray heating, including
hydrodynamic relaxation and heat flow on picosecond to millisecond timescales,
is modelled using radiation hydrocode simulation, finite element analysis, and
thermodynamic calculations. Assessing the potential for target survival over
one or more exposures, and resistance to damage arising from heating and
resulting mechanical stresses, this study doubles as an investigation into the
performance of diamond-anvil high pressure cells under high x-ray fluences.
Long used in conjunction with synchrotron x-ray radiation and high power
optical lasers, the strong confinement afforded by such cells suggests novel
applications at emerging high intensity x-ray facilities and new routes to
studying thermodynamic equilibrium states of warm, very dense matter.
