Characterizing plasma conditions in radiatively heated solid-density samples with x-ray Thomson scattering

Abstract

We have developed an experimental platform to generate radiatively heated solid density samples for warm dense matter studies at the OMEGA laser facility. Cylindrical samples of boron and beryllium are isochorically-heated by K-and L-shell emission from x-ray converter foils wrapped around the cylinders' radii. X-ray Thomson scattering (XRTS) measures the temperature and the ionization state of the samples as function of time. Temperatures approach 10 eV, and the ionization states are found to be ZB = 3 and ZBe = 2. Radiation hydrodynamics simulations were performed to confirm a homogeneous plasma state exists in the center of the sample for the duration of the experiment. Results from the study can be extended to improve understanding of radiative heating processes in the warm dense matter regime.

Thermomechanical response of thickly tamped targets and diamond anvil cells under pulsed hard x-ray irradiation

“…Intense x-rays also rapidly heat matter 3,7,9,11,[26][27][28][29][30] . This energy deposition may be introduced deliberately (e.g.…”

“…to optical lasers or ion beams 7,27,30 , and scaling up of targets to enable larger irradiated volumes 7,30 . X-ray heating performed with large optical laser 11,30 , pulsed-power 25 , and free electron laser (FEL) 3,7,9,11,26,27,29 facilities has been demonstrated. Many of these studies used lower photon energies (hundreds of eV to several keV) which can still limit the potential thickness and materials of target components and hence experimental timescales.…”

“…Free electron lasers and other high-brightness x-ray sources operating in the hard x-ray regime above ∼10 keV (Table I) allow for substantial scaling up of target dimensions and experimental timescales. At x-ray energies exceeding ∼10 keV, absorption lengths in even heavy-element solids exceed several µm enabling large volume homogenous irradiation 7,30 .…”

Properties of carbon up to 10 million kelvin from Kohn-Sham density functional theory molecular dynamics

“…The 8000 atom calculation agrees well with the predictions based on smaller cell sizes, but one significant advantage becomes evident: we can reach very small k values that extrapolate nicely to the compressibility limit S ii (k = 0) = k B T κ T , where k B is the Boltzmann constant and κ T is the compressibility. This is of crucial importance for X-ray Thomson scattering experiments [53][54][55] and the measurement of ion acoustic modes [52].…”

The Relevance of Electronic Perturbations in the Warm Dense Electron Gas

“…Some exact conditions imposed for chemistry and solid-state physics are not relevant to WDM. For example, in contrast to solid-state physics, the surface energy has no significance in WDM, because the generated samples have no well defined surface, but rather transition to a plasma state [57][58][59] . Conversely, there are properties that are highly important in WDM, but have little value for solid-state physics.…”