Speaker
Ulf Zastrau
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P1.2003.pdf
Ionization and structural dynamics in solid hydrogen and deuterium
U. Zastrau1, S. Göde1, C. Rödel2, 3, 4, M. Nakatsutsumi1, T. Feigl5, K. Appel1, B. Chen6,
T. Döppner7, T. Fennel8, T. Fiedler5, L. B. Fletcher3, E. Förster2, 4, E. Gamboa3,
D. O. Gericke9, C. Grote-Fortmann1, V. Hilbert10, L. Kazak8, T. Laarmann11, H. J. Lee3,
P. Mabey12, F. Martinez8, K.-H. Meiwes-Broer8, A. Przystawik13, S. Roling14,
S. Skruszewicz2, 4, M. Shihab8, 15, J. Tiggesbäumer8, S. Toleikis13, M. Wünsche2, 4,
H. Zacharias14, S. H. Glenzer3, and G. Gregori12
1
European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany
2
Institute of Optics and Quantum Electronics, Friedrich-Schiller University Jena, Germany
3
Stanford Linear Accelerator Center (SLAC), Menlo Park, CA 94025, USA
4
Helmholtz Institute Jena, Fröbelstieg 3, 07743 Jena, Germany
5
optiX fab GmbH, Hans-Knöll-Strasse 6, 07745 Jena
6
China Academy of Engineering Physics (CAEP), Mianyang, China
7
Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
8
Institut für Physik, Universität Rostock, 18051 Rostock, Germany
9
Centre for Fusion, Space and Astrophysics, University of Warwick, UK
10
Institute of Applied Physics, Friedrich-Schiller University Jena, 07745 Jena, Germany
11
The Hamburg Centre for Ultrafast Imaging CUI, Hamburg, Germany
12
Department of Physics, Clarendon Laboratory, University of Oxford, United Kingdom
13
Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
14
Physikalisches Institut, Westfälische Wilhelms-Universität, 48149 Münster, Germany
15
Department of Physics, Faculty of Science, Tanta University, Egypt
The thermodynamic properties of even the simplest element hydrogen remain elusive
when it comes to extreme conditions. Knowledge of the equation of state of hydrogen and its
isotope deuterium is hence critical for modeling stellar and planetary interiors, as well as for
ICF experiments. Microscopic properties related to reflectivity, electrical and thermal
conductivity are tied to dynamic energy transport between electrons and ions.
In 2014, we reported on time-resolved XUV measurements [1] where ultra-fast
electron heating is initiated by a 1013 W/cm² intense 300 fs short burst from the FLASH
XUV-FEL at 13.5 nm wavelength. A second pulse probes the sample via XUV scattering at
variable time delay. From the ion-ion structure factor S(k∼0), we found that the molecular
ice dissociates in 0.9 ps, transitioning into a dense atomic plasma with a final ion temperature
≤ 1 eV at 0.08 g/cm3, which poses several challenges to the employed plasma models and
equation-of-state tables.
New unpublished data obtained in 2015 with 60 fs temporal resolution employed a
Schwarzschild EUV microscope [2] capable of single-shot sub-µm imaging. We monitored
the hydrogen jet’s structure by single-shot Mie scattering patterns. The time-resolved
scattering suggests that 500 fs after XUV pump photo- and impact ionization have reached a
maximum and subsequently the solid-plasma transition takes place due to electron-ion heat
transfer, and is finished around 700 fs after excitation. First microscopic particle-in-cell
simulations support this interpretation. We also present an outlook about repeating the
experiment on deuterium, where the electronic excitation is comparable to hydrogen while
the electron-ion energy transfer is slower due to the heavier deuteron mass.
[1] U. Zastrau, P. Sperling, et al., Physical Review Letters 112, 105002 (2014).
[2] U. Zastrau, C. Rödel, et al., Review of Scientific Instruments 89, 023703 (2018).
